Effects of primrose oil


Evening primrose oil (EPO

Trial 1

In this trial, 49 people with rheumatoid arthritis who were on non-steroidal anti-inflammatory drugs (NSAIDs) were randomised to take one of the following once a day for 12 months:

  • 6 g (540 mg GLA) EPO
  • EPO with fish oil
  • placebo tablets.

Participants were asked to take their normal dose of NSAIDs during the first three months of the trial but were advised to reduce or stop it depending on their symptoms afterwards.

  • 94% of participants who got EPO alone and 93% who received EPO combined with fish oil reported a significant improvement of disease-related symptoms, including pain and morning stiffness, compared to only 30% of the placebo group – this was a significant difference.
  • EPO was also significantly effective in reducing the use of NSAIDs during the trial period.
  • Most participants’ symptoms came back during the three months that followed treatment, so EPO didn’t seem to alter the long-term disease activity.
  • Two participants on EPO withdrew from the trial because of nausea and diarrhoea.

Trial 2

Researchers evaluated the outcome of 40 people with rheumatoid arthritis who received daily doses of either 6 g EPO (540 mg GLA) or olive oil for six months.

  • Participants given EPO had a significant improvement in morning stiffness compared to participants given olive oil, but there were no significant differences between both treatment groups with respect to pain reduction and overall disease severity.
  • Most participants in this trial didn’t stop taking NSAIDs.
  • Four out of 19 participants taking EPO had to withdraw because of nausea, flu-like symptoms or their condition getting worse.

Evening primrose oil: benefits, dosage, side-effects

Find out all about evening primrose oil, including what it does, the benefits to taking it and how much you might need

Written by Cheryl Freedman on December 11, 2018
Reviewed by Dr Sarah Schenker on December 18, 2018


What is evening primrose oil and what does it do?

Evening primrose oil is the oil extracted from the seeds of the yellow evening primrose wildflower, Oenothera biennis. It is a rich source of linoleic acid and gamma-linoleic acid (GLA), both omega-6 essential fatty acids.1,2

GLA is used to make hormone-like substances called prostaglandins, which can help calm inflammation.3 Many women use evening primrose oil (EPO) to manage symptoms of pre-menstrual syndrome (PMS) and menopause, such as hot flushes.4 EPO is also used to help ease skin conditions including eczema and acne.5

Evening primrose oil is most often taken as capsules but sometimes comes as a liquid.

Benefits of evening primrose oil

What does evening primrose do in the body?

Indigenous Americans would use the leaves and bark of the evening primrose plant for stomach and liver complaints.6 EPO is also used as a traditional herbal remedy to relieve the itching that’s associated with dry skin conditions.7

The evidence for taking EPO is still inconclusive, but some studies show it may be helpful for:

  • menopause symptoms – there’s a lot of anecdotal evidence from menopausal women that using evening primrose oil can ease hot flushes. One 2013 study found taking EPO for six weeks could relieve the frequency, intensity and length of hot flushes. The women in the study also reported a significant improvement in their sense of wellbeing.8
  • pre-menstrual syndrome (PMS) – many women take EPO for PMS symptoms such as water retention, breast tenderness and low mood; the Royal College of Obstetricians and Gynaecologists reports that it can ease breast tenderness9. A 1983 study concluded that taking EPO was ‘highly effective’ for treating symptoms of PMS,10 but more recent research is needed.
  • dry skin conditions – the European Medicines Agency says EPO can be used for relief of itching in short-term and long-term dry skin conditions,11 and is often taken by people with eczema to help prevent dry, itchy skin.12 But a 2013 Cochrane Review concluded evening primrose oil is no more effective than a placebo in treating eczema.13
  • acne – it’s thought the GLA in evening primrose oil may improve acne, by reducing inflammation and minimising scarring; one 2014 Korean study found that GLA reduced inflammation in acne sufferers.14 But more evidence is needed before EPO can be recommended as an acne treatment.
  • arthritis – EPO is often used by those with rheumatoid arthritis to ease pain and stiffness. One study found taking it helped ease morning stiffness in patients with the condition.15 Versus Arthritis says, while the evidence isn’t conclusive, it may ‘help in the regulation of pain and inflammation’.16

If you’re interested in taking evening primrose oil, talk to your GP or a healthcare professional first.


How much evening primrose oil is safe to take?

There is no official upper limit for EPO, but the European Medicines Agency warns that children under 12 should not take it.17

You should also avoid taking EPO if you:18

  • are on blood thinning drugs like warfarin, as EPO has blood-thinning effects
  • are due to have surgery in two weeks
  • have epilepsy, schizophrenia or any other seizure disorder, as there’s a risk evening primrose oil may increase risk of seizure
  • are pregnant, as EPO can cause complications

Always check with your healthcare professional before taking evening primrose oil and read the label, as dose instructions may vary between products.


What are the side-effects of taking evening primrose oil?

Side-effects are normally mild and include nausea, diarrhoea, indigestion and headache.19

Very rarely, EPO can cause an allergic reaction. If you notice a rash, itching or breathing difficulties after taking it, seek medical attention immediately.20

Shop EPO

Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.

1. ScienceDirect. Primrose oil
2. Marcus MacGill. Medical News Today. What are the uses of primrose oil?
3. Ricciotti E, FitzGerald GA. Prostaglandins and inflammation
4. Dr Deborah Rose Wilson. Healthline. 10 Benefits of Evening Primrose Oil and How To Use It
5. As above
6. Encyclopedia.com. Evening primrose oil
7. European Medicines Agency. Evening primrose oil
8. Farzaneh F, et al. The effect of oral evening primrose oil on menopausal hot flashes: a randomized clinical trial
9. Royal College of Obstetricians and Gynaecologists. Managing premenstrual syndrome
10. Horrobin DF. The role of essential fatty acids and prostaglandins in the premenstrual syndrome
11. As Source 7
12. As Source 4
13. Cochrane. Oral evening primrose oil and borage oil for eczema
14. Jung YJ, et al. Effect of dietary supplementation with omega-3 fatty acid and gamma-linolenic acid on acne vulgaris: a randomised, double-blind, controlled trial
15. Brzeski M, Madhok R, Capell HA. Evening primrose oil in patients with rheumatoid arthritis and side-effects of non-steroidal anti-inflammatory drugs
16. Versus Arthritis. Complementary and alternative medicines for the treatment of rheumatoid arthritis
17. As Source 7
18. Mayo Clinic. Evening primrose
19. As Source 7
20. As Source 4

Evening Primrose Oil


  • Evening primrose is a plant native to North America, but it grows in Europe and parts of the Southern hemisphere as well. It has yellow flowers that bloom in the evening. Evening primrose oil contains the fatty acid gamma-linolenic acid (GLA).
  • Native Americans used the whole plant for bruises and its roots for hemorrhoids. The leaves were traditionally used for minor wounds, gastrointestinal complaints, and sore throats.
  • Today, people use evening primrose oil dietary supplements for eczema (a condition involving red, swollen, itchy skin, sometimes caused by allergies), rheumatoid arthritis, premenstrual syndrome (PMS), breast pain, menopause symptoms, and other conditions.
  • Evening primrose oil is obtained from the seeds of the evening primrose and is usually sold in capsule form.

How Much Do We Know?

  • Many studies in people have evaluated evening primrose oil for eczema, PMS, or breast pain. Smaller numbers of studies have evaluated it for other health conditions.

What Have We Learned?

  • There’s not enough evidence to support the use of evening primrose oil for any health condition.
  • According to a comprehensive 2013 evaluation of the evidence, evening primrose oil, taken orally (by mouth), is not helpful for relieving symptoms of eczema.
  • Most studies of evening primrose oil for PMS have not found it to be helpful.
  • Studies of evening primrose oil for breast pain have had conflicting results.
  • A small amount of evidence suggests that evening primrose oil might be helpful for diabetic neuropathy (nerve problems caused by diabetes).

What Do We Know About Safety?

  • Evening primrose oil is probably safe for most people when taken for short periods of time. There can be mild side effects, such as stomach upset and headache.
  • The safety of long-term use of evening primrose oil has not been established.
  • Evening primrose oil may increase the risk of some complications of pregnancy. Talk with your health care provider if you’re considering using evening primrose oil during pregnancy.
  • Evening primrose oil may increase bleeding in people who are taking the anticoagulant (blood thinning) medication warfarin (Coumadin).

Keep in Mind

  • Tell all your health care providers about any complementary or integrative health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

Evening Primrose

Generic Name: evening primrose (EVE ning PRIM rose)
Brand Name: Primrose Oil, Evening Primrose Oil

Medically reviewed by Drugs.com on Aug 5, 2019 – Written by Cerner Multum

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What is evening primrose?

Evening primrose is a plant also known as Primrose Seed Oil, Aceite de Onagra, Acide Cis-linoléique, Cis-Linoleic Acid, EPO, Fever Plant, Herbe-aux-ânes, Huile de Graines d’Onagre, Huile D’Onagre, Huile de Primerose, Huile de Primevère Vespérale, Jambon de Jardinier, Jambon du Paysan, King’s Cureall, Mâche Rouge, Night Willow-Herb, Oenothera biennis, Oenothera muricata, Oenothera purpurata, Oenothera rubricaulis, Oenothera suaveolens, Onagra biennis, Onagraire, Onagre Bisannuelle, Onagre Commune, Primevère du Soir, Scabish, Sun Drop, and other names.

Evening primrose has been used in alternative medicine as a possibly effective aid in treating nerve damage caused by diabetes, and osteoporosis.

Evening primrose has also been used to treat asthma, eczema, attention deficit- hyperactivity disorder (ADHD), hepatitis B, high cholesterol, liver cancer, breast pain, obesity, menopausal hot flashes and night sweats, premenstrual syndrome (PMS), and skin or joint symptoms of psoriasis. However, research has shown that evening primrose may not be effective in treating these conditions.

Evening primrose may have been combined with other plants or extracts in a specific preparation to treat these conditions .

Other uses not proven with research have included chronic fatigue syndrome, dyslexia, coordination and movement problems, diaper rash, dry eyes, rheumatoid arthritis, multiple sclerosis, ulcerative colitis, schizophrenia, Alzheimer’s and other conditions.

It is not certain whether evening primrose is effective in treating any medical condition. Medicinal use of this product has not been approved by the FDA. Evening primrose should not be used in place of medication prescribed for you by your doctor.

Evening primrose is often sold as an herbal supplement. There are no regulated manufacturing standards in place for many herbal compounds and some marketed supplements have been found to be contaminated with toxic metals or other drugs. Herbal/health supplements should be purchased from a reliable source to minimize the risk of contamination.

Evening primrose may also be used for purposes not listed in this product guide.

Important Information

Follow all directions on the product label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use this product if you are allergic to evening primrose or if you have:

  • a bleeding or blood clotting disorder; or

  • if you are pregnant.

Ask a doctor, pharmacist, or other healthcare provider if it is safe for you to use this product if you have:

  • epilepsy or a seizure disorder; or

  • schizophrenia.

Evening primrose is considered likely unsafe to use during pregnancy. Do not use this product without medical advice if you are pregnant.

Evening primrose is considered possibly safe to use while breast-feeding. Do not use this product without medical advice if you are breast-feeding a baby.

Do not give any herbal/health supplement to a child without medical advice.

How should I take evening primrose?

When considering the use of herbal supplements, seek the advice of your doctor. You may also consider consulting a practitioner who is trained in the use of herbal/health supplements.

If you choose to use evening primrose, use it as directed on the package or as directed by your doctor, pharmacist, or other healthcare provider. Do not use more of this product than is recommended on the label.

Do not use different formulations (e.g., tablets, liquids, and others) of evening primrose at the same time, unless specifically directed to do so by a health care professional. Using different formulations together increases the risk of an overdose of evening primrose.

Call your doctor if the condition you are treating with evening primrose does not improve, or if it gets worse while using this product.

Evening primrose can affect blood-clotting and may increase your risk of bleeding. If you need surgery, dental work, or a medical procedure, stop taking evening primrose at least 2 weeks ahead of time.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra evening primrose to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking evening primrose?

Follow your healthcare provider’s instructions about any restrictions on food, beverages, or activity.

Avoid using evening primrose together with other herbal/health supplements that can also affect blood-clotting. This includes angelica (dong quai), capsicum, clove, danshen, garlic, ginger, ginkgo, horse chestnut, panax ginseng, poplar, red clover, saw palmetto, turmeric, and willow.

Evening primrose side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Although not all side effects are known, evening primrose is thought to be likely safe for most people when used for up to a year.

Stop using evening primrose and call your healthcare provider at once if you have:

  • easy bruising or bleeding; or

  • a bleeding that will not stop.

Common side effects may include:

  • upset stomach;

  • nausea;

  • diarrhea; or

  • headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect evening primrose?

Do not take evening primrose without medical advice if you are using any of the following medications:

This list is not complete. Other drugs may interact with evening primrose, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this product guide.

Further information

  • Consult with a licensed healthcare professional before using any herbal/health supplement. Whether you are treated by a medical doctor or a practitioner trained in the use of natural medicines/supplements, make sure all your healthcare providers know about all of your medical conditions and treatments.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2018 Cerner Multum, Inc. Version: 6.02.

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Evening Primrose Oil

Medically reviewed by Drugs.com. Last updated on Feb 27, 2019.

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Scientific Name(s): Oenothera biennis L.
Common Name(s): Common evening primrose, Evening primrose

Clinical Overview


Evidence suggests that evening primrose oil may be effective for treating rheumatoid arthritis, injection site skin reactions, and diabetic neuropathy, but is lacking to support its place in the treatment of atopic eczema/dermatitis syndrome, menopausal vasomotor symptoms, mastalgia, or multiple sclerosis. In combination with vitamin D, evening primrose oil has improved glycemic and lipid profiles in women with gestational diabetes.

Evening primrose oil has been administered orally in clinical trials at doses between 1 and 8 g/day in adults and 2 and 4 g/day in children. The typical content of gamma-linolenic acid (GLA) in the oil is 8% to 10%.


No contraindications have been identified.


Information regarding safety and efficacy in pregnancy and lactation is lacking. A case report exists of transient petechiae in a newborn following oral and intravaginal use of evening primrose oil for cervical ripening for a week prior to the infant’s birth. Both linoleic and GLA are normally present in breast milk, and it is reasonable to assume that evening primrose oil may be taken while breast-feeding.

See Drug Interactions section.

Evening primrose oil was previously suspected to lower the seizure threshold in schizophrenic patients; however, this is now disputed.

No toxicity, carcinogenicity, or teratogenicity has been reported.

Scientific Family

  • Onagraceae


The evening primrose is a large, delicate wildflower native to North America with blooms usually lasting only 1 evening, but it is not a true primrose. Primrose is a yellow-flowered annual or biennial and can grow from 1 to 3 m in height. The fruit is a dry pod approximately 5 cm long that contains many small seeds.1, 2, 3


Seeds from O. biennis contain 14% of a fixed oil known as evening primrose oil that can contain 50% to 70% cis-linoleic acid and 7% to 10% cis-GLA. Wild varieties of O. biennis contain highly variable amounts of linoleic acid and GLA; however, extensive crossbreeding has produced a commercial variety that consistently yields oil with 72% cis-linoleic acid and 9% GLA.2, 3 Also found are cis-6,9,12-octadecatrienoic acid; small amounts of oleic, palmitic, and stearic acids; steroids; campesterol; and beta-sitosterol. Mucilage and tannin in the plant parts have been analyzed.2

Uses and Pharmacology

Essential fatty acids are important as cellular structural elements and as precursors of prostaglandins. Essential fatty acids are the biologically active parts of polyunsaturated fats that cannot be manufactured by the body and must be provided by the diet in relatively large amounts.2 Recommended intake of linoleic acid and alpha-linolenic acid are 12 g and 1.1 g, respectively, for women 19 to 30 years of age.4

In theory, the GLA provided by evening primrose oil can be converted directly to the prostaglandin precursor di-homo-gamma-linolenic acid and might be beneficial to individuals unable to metabolize cis-linoleic acid to GLA or those with low dietary intake of cis-linoleic acid. However, this relationship was not proven in a pharmacokinetic study in healthy participants.5

Atopic dermatitis/Dermatologic disorders

Clinical data

Atopic eczema/dermatitis syndrome has been recommended by an international task force to encompass all forms of eczema, including atopic dermatitis.67 A number of reviews and randomized clinical trials show a lack of support for the use of evening primrose oil for atopic dermatitis.6, 7, 8, 9 Many of the trials are of poor quality and have apparent issues of bias.9, 10, 11 In 2013, a Cochrane review evaluated 19 placebo-controlled, randomized clinical trials conducted in adults and children that assessed evening primrose oil for the treatment of signs and symptoms of eczema. Meta-analyses conducted with 7 studies using participant-reported improvements (n = 176) and 8 using physician-assessed improvements (n = 289) support previous reports of the lack of effectiveness of evening primrose oil.67

While an older review suggested promising results12 the most comprehensive meta-analysis to date did not establish efficacy.10 Clinical studies continue to be conducted, with a gradual time-dependent improvement suggested.13

Cardiovascular disease

There is no recent evidence to support older studies38, 39, 40 suggesting that evening primrose oil reduced platelet aggregation. An observational study suggests serum linoleic acid may protect against ischemic stroke.41 Despite limited older trials in humans and numerous studies using rats and rabbits, there are no recent randomized, controlled trials demonstrating a beneficial effect of evening primrose oil on cholesterol levels or serum lipids. A more recent randomized, controlled trial found no effect on endothelial function or vascular tone with evening primrose oil supplementation.42

Diabetic neuropathy

A review of 3 randomized, controlled trials suggested evening primrose oil might improve symptoms of diabetic neuropathy. Dosages in these trials ranged from 360 to 480 mg GLA daily. Few adverse effects were noted in these trials, and there was no increase in blood glucose levels.43, 44

As a component of medical nutrition therapy for patients with type 2 diabetes, the American Diabetes Association Standards of Care (2014) recommends higher quality dietary fat intake, as an alternative to decreased fat intake, by replacing saturated and/or trans fats with mono- and poly-unsaturated fatty acids in the diet. This Mediterranean-style approach to eating may improve glycemic control and cardiovascular disease risk factors (moderate-quality evidence).69

Dyslexia/Brain development

Current interest in the use of evening primrose oil for enhancing intellectual performance in children is yet to be validated by rigorous research. Studies conducted in children with dyslexia suggest improved reading, spelling, and behavior45, 46 while a Cochrane systematic review and a long-term study (39 months) showed no long-term benefit in infants fed formula supplemented with long-chain polyunsaturated fatty acids.47, 48 An open study found benefit with the use of a fish oil and evening primrose oil combination in children with dyslexia.49

Eye conditions

Study results disagree as to the effect of evening primrose oil on dry eye syndrome37, 50, 51 and there is concern regarding high intake of linoleic and linolenic acid and the risk of cataract development.52, 53

Gestational diabetes mellitus


Topical application of saponified evening primrose oil reduced ultraviolet B-induced hyperpigmentation, while a decrease in melanin production has been demonstrated in vivo with the saponified oil.54


Local injection-site reactions after subcutaneous injections of 5-azacitidine and bortezomib have been reduced with topical application of evening primrose oil.55, 66 Additionally, the time to complete resolution of bortezomib-induced skin reactions was shortened (median, 4 days).66


There is little evidence to support the efficacy of evening primrose oil in treatment of mastalgia, with most trials finding no advantage over placebo.14, 15, 16, 17 Although 23% taking evening primrose oil experienced a complete response in a small randomized, comparator trial (n = 135) after 6 months of therapy, this response was statistically significantly less than the group receiving the study drug Centchroman, a novel nonsteroidal selective anti-estrogen oral contraceptive, which showed an 86% response (P < 0.05).65 A meta-analysis of clinical trials found no evidence of effect in pain relief, with a mean pain score difference of -2.78 (95% confidence interval, -7.97 to 2.4).18

Menopause-associated vasomotor symptoms/premenstrual syndrome

A number of reviews and randomized clinical trials found no evidence of benefit with evening primrose oil use for menopausal vasomotor symptoms or premenstrual syndrome.19, 20, 21, 22, 23, 24, 25 In 2004, the North American Menopause Society did not support the use of evening primrose oil for menopausal vasomotor symptoms given the lack of efficacy data, but this has not been recently reviewed.26 The Society of Obstetricians and Gynaecologists of Canada revised clinical practice guidelines (2014) on managing menopause do not recommend evening primrose oil for reducing menopausal symptoms based on a lack of evidence to support clinical benefit.71 A 2013 randomized, double-blind, placebo-controlled trial in 56 menopausal treatment-naïve Iranian women (with at least 4 hot flashes a day) documented significant changes from baseline for hot flash severity, but not in their frequency or duration, in those randomized to receive 1,000 mg/day evening primrose oil extract for 6 weeks. Additionally, 3 Hot Flash Related Daily Interference Scale subscores improved significantly: social activity, relations with others, and sexuality. Mild self-limiting nausea was reported in 2 women in the intervention group.68

Multiple sclerosis

Despite a seemingly valid theoretical basis for the use of evening primrose oil in multiple sclerosis, there is a lack of evidence to substantiate its use.27 A review of 3 trials suggested an effect with a slower progression of disability and improved relapse (severity and duration) scores, but a randomized, controlled trial, not included in the review, showed no effect.28, 29, 30, 31, 32 No new trials have been published since the 1980s.

Myalgic encephalomyelitis (chronic fatigue syndrome)

A theoretical model has been proposed for a place in therapy for evening primrose oil in this condition. Clinical trials are lacking.56

Rheumatoid arthritis

A Cochrane review of randomized trials comparing evening primrose oil with placebo suggests some benefit in using evening primrose oil for rheumatoid arthritis, despite the relative poor quality of the individual studies. A trend toward reduction of morning stiffness and joint tenderness, as well as pain relief, has been shown. The authors found the evidence to be sufficient to warrant further larger trials to provide conclusive results and define optimal dosage and duration of therapy.34 These findings are supported by other reviews, especially with regard to effective duration of therapy.35, 36 A more recent randomized, double-blind, placebo-controlled study enrolling 90 patients with primary Sjögren syndrome found no statistically significant in patient fatigue with a higher dosage after 6 months of therapy.37


An exploratory study found an increase in urinary citrate excretion following 1,000 mg/day of evening primrose oil.57


Evening primrose oil has been administered orally in clinical trials at doses between 6 and 8 g/day in adults and 2 and 4 g/day in children. Wide-ranging doses of 0.27 g to 6.48 g GLA per day have been used in clinical studies in mastalgia.24 The typical content of GLA in the oil is 8% to 10%.2

Evening primrose oil 1 g/day in combination with vitamin D3 (1,000 units/day) has been used to improve glycemic and lipid profiles in women with gestational diabetes.70

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Both linoleic and GLA are normally present in breast milk, and it is reasonable to assume that evening primrose oil may be taken while breast-feeding. A case report exists of transient petechiae in a newborn following oral and intravaginal use of evening primrose oil for cervical ripening for a week prior to the infant’s birth. In vitro and in vivo animal studies suggest inhibition of platelet function in the newborn may have been caused by exposure to evening primrose oil.58

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Agents with antiplatelet roperties: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of agents with antiplatelet properties. Bleeding may occur. Consider therapy modification.59, 60, 61, 62

Anticoagulants: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of anticoagulants. Bleeding may occur. Consider therapy modification.59, 60, 61, 62

Herbs (anticoagulant/antiplatelet properties): Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of other herbs (anticoagulant/antiplatelet properties). Bleeding may occur. Consider therapy modification.59, 60, 61, 62

Nonsteroidal anti-inflammatory agents: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of nonsteroidal anti-inflammatory agents. Bleeding may occur. Consider therapy modification.59, 60, 61, 62

Salicylates: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of salicylates. Bleeding may occur. Consider therapy modification.59, 60, 61, 62

Thrombolytic agents: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of thrombolytic agents. Bleeding may occur. Consider therapy modification.59, 60, 61, 62

Adverse Reactions

Two clinical studies conducted in the 1980s among individuals with schizophrenia led to a concern that evening primrose oil might lower the seizure threshold. However, other factors may account for the observed seizures: the few participants who developed seizures were taking concomitant medicines (phenothiazines) known to lower the seizure threshold, and also a link has been described between schizophrenia and epilepsy. There are no further reports of seizures related to evening primrose oil, which may actually have a protective effect.63

A case report of lipoid pneumonia secondary to long-term evening primrose oil use exists.64

There is no recent evidence to support older studies suggesting that evening primrose oil reduced platelet aggregation.38, 39, 40


Animal toxicological studies and extensive use of evening primrose oil over many years revealed no data of concern. As a nutritional supplement, the maximum label-recommended daily dose of evening primrose oil is approximately 4 g, containing 300 to 360 mg of GLA.2

1. Oenothera biennis L. USDA, NRCS. 2007. The PLANTS database (http://plants.usda.gov, 13 February 2007). National Plant Data Team, Greensboro, NC 27401-4901 USA.2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. 2nd ed. Hoboken, NJ: Wiley-Interscience; 2003.3. DerMarderosian A, Liberti L. Natural Product Medicine. Philadelphia, PA: George F. Stickley Co; 1988.4. Dietary Guidelines for Americans 2010. U.S. Department of Health and Human Services. U.S. Department of Agriculture. http://www.dietaryguidelines.gov. Accessed January 9, 2012.5. Martens-Lobenhoffer J, Meyer FP. Pharmacokinetic data of gamma-linoleic acid in healthy volunteers after the administration of evening primrose oil ( Epogram). Int J Clin Pharmacol Ther. 1998;36;363-366.97073496. Bendich A. The potential for dietary supplements to reduce premenstrual syndrome (PMS) symptoms. J Am Coll Nutr. 2000;19:3-12.7. Ernst E, Pittler MH, Stevinson C. Complementary/alternative medicine in dermatology: evidence-assessed efficacy of two diseases and two treatments. Am J Clin Dermatol. 2002;3:341-348.120696408. Hoare C, Li Wan Po A, Williams H. Systematic review of treatments for atopic eczema. Health Technol Assess. 2000;4(37):1-191.9. Williams HC, Grindlay DJ. What’s new in atopic eczema? An analysis of the clinical significance of systematic reviews on atopic eczema published in 2006 and 2007. Clin Exp Dermatol. 2008;33(6):685-688.1869124410. Van Gool CJ, Zeegers MP, Thijs C. Oral essential fatty acid supplementation in atopic dermatitis — a meta-analysis of placebo-controlled trials. Br J Dermatol. 2004;150(4):728-740.1509937011. Williams HC. Evening primrose oil for atopic dermatitis. BMJ. 2003;327(7428):1358-1359.1467085112. Morse PF, Horrobin DF, Manku MS, et al. Meta-analysis of placebo-controlled studies of the efficacy of Epogam in the treatment of atopic eczema. Relationship between plasma essential fatty acid changes and clinical response. Br J Dermatol. 1989;121(1):75-90.266762013. Senapati S, Banerjee S, Gangopadhyay DN. Evening primrose oil is effective in atopic dermatitis: a randomized placebo-controlled trial. Indian J Dermatol Venereol Leprol. 2008;74(5):447-452.1905240114. Goyal A, Mansel RE, Efamast Study Group. A randomized multicenter study of gamolenic acid (Efamast) with and without antioxidant vitamins and minerals in the management of mastalgia. Breast J. 2005;11(1):41-47.1564707715. Qureshi S, Sultan N. Topical nonsteroidal anti-inflammatory drugs versus oil of evening primrose in the treatment of mastalgia. Surgeon. 2005;3(1):7-10.1578978616. Blommers J, de Lange-de Klerk ES, Kuik DJ, Bezemer PD, Meijer S. Evening primrose oil and fish oil for severe chronic mastalgia: a randomized, double-blind, controlled trial. Am J Obstet Gynecol. 2002;187(5):1389-1394.1243953617. Pruthi S, Wahner-Roedler DL, Torkelson CJ, et al. Vitamin E and evening primrose oil for management of cyclical mastalgia: a randomized pilot study. Altern Med Rev. 2010;15(1):59-67.2035926918. Srivastava A, Mansel RE, Arvind N, et al. Evidence-based management of mastalgia: a meta-analysis of randomised trials. Breast. 2007;16(5):503-512.1750988019. Philp HA. Hot flashes—a review of the literature on alternative and complementary approaches. Altern Med Rev. 2003;8(3):284-302.1294623920. Fugate SE, Church CO. Nonestrogen treatment modalities for vasomotor symptoms associated with menopause. Ann Pharmacother. 2004;38(9):1482-1499.1529249821. Huntley AL, Ernst E. A systematic review of herbal medicinal products for the treatment of menopausal symptoms. Menopause. 2003;10(5):465-476.1450160922. Kronenberg F, Fugh-Berman A. Complementary and alternative medicine for menopausal symptoms: a review of randomized, controlled trials. Ann Intern Med. 2002;137(10):805-814.1243521723. Stevinson C, Ernst E. Complementary/alternative therapies for premenstrual syndrome: a systematic review of randomized controlled trials. Am J Obstet Gynecol. 2001;185(1):227-235.1148393324. Whelan AM, Jurgens TM, Naylor H. Herbs, vitamins and minerals in the treatment of premenstrual syndrome: a systematic review. Can J Clin Pharmacol. 2009;16(3):e407-e429.1992363725. Wong VC, Lim CE, Luo X, Wong WS. Current alternative and complementary therapies used in menopause. Gynecol Endocrinol. 2009;25(3):166-174.1934770626. North American Menopause Society. Treatment of menopause-associated vasomotor symptoms: position statement of The North American Menopause Society. Menopause. 2004;11(1):11-33.1471617927. Namaka M, Crook A, Doupe A, et al. Examining the evidence: complementary adjunctive therapies for multiple sclerosis. Neurol Res. 2008;30(7):710-719.1863142828. Schwarz S, Leweling H. Multiple sclerosis and nutrition. Mult Scler. 2005:11(1):24-32.1573226329. Dworkin RH, Bates D, Millar JH, Paty DW. Linoleic acid and multiple sclerosis: a reanalysis of three double-blind trials. Neurology. 1984;34(11):1441-1445.638753430. McGregor L, Smith AD, Sidey M, Belin J, Zilkha KJ, McGregor JL. Effects of dietary linoleic acid and gamma linolenic acid on platelet of patients with multiple sclerosis. Acta Neuro Scand. 1989;80(1):23-27.278203831. Horrobin DF. Multiple sclerosis: the rational basis for treatment with colchicine and evening primrose oil. Med Hypothesis. 1979;5(3):365-378.31349932. Namazi MR. The beneficial and detrimental effects of linoleic acid on autoimmune disorders. Autoimmunity. 2004;37(1):73-75.1511531533. Calder PC, Yaqoob P, Thies F, Wallace FA, Miles EA. Fatty acids and lymphocyte function. Br J Nutr. 2002;87(suppl 1):S31-S48.1189515434. Little CV, Parsons T. Herbal therapy for treating rheumatoid arthritis. Cochrane Database Syst Rev. 2000;(1):CD002947.35. Darlington LG, Stone TW. Antioxidants and fatty acids in the amelioration of rheumatoid arthritis and related disorders. Br J Nutr. 2001;85(3):251-269.1129907236. Belch JJ, Hill A. Evening primrose oil and borage oil in rheumatologic conditions. Am J Clin Nutr. 2000;71(suppl 1):352S-356S.1061799637. Theander E, Horrobin DF, Jacobsson LT, Manthorpe R. Gammalinolenic acid treatment of fatigue associated with primary Sjögren’s syndrome. Scand J Rheumatol. 2002;31(2):72-79.1210965038. Walker T, Singh PK, Wyatt KM, O’Brien PM. The effect of prostanoid precursors and inhibitors on platelet angiotensin II binding. J Obstet Gynaecol. 1999;19(1):56-58.1551222439. Pirich C, Gaszo A, Granegger S, Sinzinger H. Effects of fish oil supplementation on platelet survival and ex vivo platelet function in hypercholesterolemic patients. Thromb Res. 1999;96(3):219-227.1058846540. Fan YY, Ramos KS, Chapkin RS. Dietary gamma-linoleic acid modulates macrophage-vascular smooth muscle cell interactions. Evidence for a macrophage-derived soluble factor that downregulates DNA synthesis in smooth muscle cells. Arterioscler Thromb Vasc Biol. 1995;15(9):1397-1403.767095441. Iso H, Sato S, Umemura U, et al. Linoleic acid, other fatty acids, and the risk of stroke. Stroke. 2002;33(8):2086-2093.1215426842. Khan F, Elherik K, Bolton-Smith C, et al. The effects of dietary fatty acid supplementation on endothelial function and vascular tone in healthy subjects. Cardiovasc Res. 2003;59(4):955-962.1455383543. Halat KM, Dennehy CE. Botanicals and dietary supplements in diabetic peripheral neuropathy. J Am Board Fam Pract. 2003;16(1):47-57.1258365044. Ford I, Cotter MA, Cameron NE, Greaves M. The effects of treatment with alpha-lipoic acid or evening primrose oil on vascular hemostatic and lipid risk factors, blood flow, and peripheral nerve conduction in the streptozotocin-diabetic rat. Metabolism. 2001;50(8):868-875.1147447245. Richardson AJ, Montgomery P. The Oxford-Durham Study: a randomized, controlled trial of dietary supplementation with fatty acids in children with developmental coordination disorder. Pediatrics. 2005;115(5):1360-1366.1586704846. Stordy BJ. Dark adaptation, motor skills, docosahexaenoic acid, and dyslexia. Am J Clin Nutr. 2000;71(1 suppl):323S-326S.1061799047. Simmer K, Patole S. Longchain polyunsaturated fatty acid supplementation in preterm infants. Cochrane Database Syst Rev. 2004;(1):CD000375.1497395648. Auestad N, Scott DT, Janowsky JS, et al. Visual, cognitive, and language assessments at 39 months; a follow-up study of children fed formulas containing long-chain polyunsaturated fatty acids to 1 year of age. Pediatrics. 2003;112(3, pt 1):e177-e183.1294930949. Lindmark L, Clough P. A 5-month open study with long-chain polyunsaturated fatty acids in dyslexia. J Med Food. 2007;10(4):662-666.1815883850. Barabino S, Rolando M, Camicione P, et al. Systemic linoleic and gamma-linolenic acid therapy in dry eye syndrome with an inflammatory component. Cornea. 2003;22(2):97-101.1260503951. Kokke KH, Morris JA, Lawrenson JG. Oral omega-6 essential fatty acid treatment in contact lens associated dry eye. Cont Lens Anterior Eye. 2008;31(3):141-146.1831335052. Lu M, Taylor A, Chylack LT, et al. Dietary fat intake and early age-related lens opacities. Am J Clin Nutr. 2005;81(4):773-779.1581785153. Seddon JM, Cote J, Rosner B. Progression of age-related macular degeneration: association with dietary fat, transunsaturated fat, nuts, and fish intake. Arch Ophthalmol. 2003;121(12):1728-1737.1466259354. Koo JH, Lee I, Yun SK, Kim HU, Park BH, Park JW. Saponified evening primrose oil reduces melanogenesis in B16 melanoma cells and reduces UV-induced skin pigmentation in humans. Lipids. 2010;45(5):401-407.2035249655. Platzbecker U, Aul C, Ehninger G, Giagounidis A. Reduction of 5-azacitidine induced skin reactions in MDS patients with evening primrose oil. Ann Hematol. 2010;89(4):427-428.1971433056. Puri BK. Long-chain polyunsaturated fatty acids and the pathophysiology of myalgic encephalomyelitis (chronic fatigue syndrome). J Clin Pathol. 2007;60(2):122-124.1693596657. Rodgers A, Lewandowski S, Allie-Hamdulay S, Pinnock D, Baretta G, Gambaro G. Evening primrose oil supplementation increases citraturia and decreases other urinary risk factors for calcium oxalate urolithiasis. J Urol. 2009;182(6):2957-2963.1984613858. Wedig KE, Whitsett JA. Down the primrose path: petechiae in a neonate exposed to herbal remedy for parturition. J Pediatr. 2008;152(1):140, 140.e1.1815491759. Mousa SA. Antithrombotic effects of naturally derived products on coagulation and platelet function. Methods Mol Biol. 2010;663:229-240.2061742160. Stanger MJ, Thompson LA, Young AJ, et al. Anticoagulant activity of select dietary supplements. Nutr Rev. 2012;70(2):107-117.2230059761. Spolarich AE, Andrews L. An examination of the bleeding complications associated with herbal supplements, antiplatelet and anticoagulant medications. J Dent Hyg. 2007;81(3):67.1790842362. Ulbricht C, Chao W, Costa D, et al. Clinical evidence of herb-drug interactions: a systematic review by the Natural Standard Research Collaboration. Curr Drug Metab. 2008;9(10):1063-1120.1907562363. Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins Leukot Essent Fatty Acids. 2007;77(2):101-103.1776491964. Rabahi MF, Ferreira AA, Madeira JG, Galvao PM, Pinto SA. Lipoid pneumonia secondary to long-term use of evening primrose oil. J Bras Pneumol. 2010;36(5):657-661.2108583265. Sharma N, Gupta A, Jha PK, Rajput P. Mastalgia Cured! Randomized trial comparing centchroman to evening primrose oil. Breast J. 2012;18(5):509-510.2289207466. Auberger J, Vogt S, Hopfinger G, Clausen J, Greil R. Topical evening primrose oil for reduction of bortezomib-induced skin reactions. Ann Hematol. 2013;92(7):995-996.2326266867. Bamford JT, Ray S, Musekiwa A, van Gool C, Humphreys R, Ernst E. Oral evening primrose oil and borage oil for eczema. Cochrane Database of Syst Rev. 2013;4:CD004416.2363331968. Farzaneh F, Fatehi S, Sohrabi MR, Alizadeh K. The effect of oral evening primrose oil on menopausal hot flashes: a randomized clinical trial. Arch Gynecol Obstet. 2013;288(5):1075-1079.2362533169. American Diabetes Association. Standards of medical care in diabetes–2014. Diabetes Care. 2014;37(suppl 1):S14-S80.2435720970. Jamilian M, Karamali M, Taghizadeh M, et al. Vitamin D and evening primrose oil administration improve glycemia and lipid profiles in women with gestational diabetes. Lipids. 2016;51(3):349-356.2678176371. Reid R, Abramson BL, Blake J, et al; Menopause and Osteoporosis Working Group. Society of Obstetricians and Gynaecologists of Canada. Managing Menopause. J Obstet Gynaecol Can. 2014;36(9):830-838.25222364


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  • Evening Primrose
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Evening primrose oil is a rich source of anti-inflammatory gamma linoleic acid (GLA). Although proponents claim that this oil may help with conditions such as eczema, dry eye, chronic pain, and women’s hormonal issues, there is insufficient evidence to support most uses. Read on to learn more about the potential health benefits and side effects of evening primrose oil.

What Is Evening Primrose Oil?

Evening primrose (Oenothera biennis) is a flowering plant belonging to the willowherb family (Onagraceae). It is native to North America but also grows wild in Europe and parts of the Southern hemisphere.

The seeds of this plant are rich in gamma linolenic acid (GLA), an omega-6 fatty acid with many potential health benefits .

Unlike evening primrose, many plants and vegetable oils contain linoleic acid, which has to be converted to GLA in the body to achieve the desirable effects. Evening primrose oil contains GLA, so it bypasses this activation step .

Essential fatty acids are necessary for maintaining good health, but cannot be made by the body – they have to be taken in through food. Their actions are diverse and include boosting skin health and hair growth, maintaining bone health, regulating metabolism, and maintaining fertility .

Gamma-linolenic acid in evening primrose oil may support brain function and decrease inflammation. It’s become a popular supplement for immune system disorders, including autoimmune diseases and conditions characterized by chronic inflammation .

It can be taken as a supplement or applied to the skin. The primary uses of the oil are for eczema, skin health, menstrual and menopausal symptoms, and lactation. It’s also used for diabetic neuropathy, premenstrual syndrome, rheumatoid arthritis, essential fatty acid deficiencies, dandruff, and some pregnancy-related complications .


The seed contains 15% proteins, 24% oil, and 43% fiber.

The fatty acid components in the seed include about 70% linoleic and 10% gamma-linolenic (GLA) acid, while the rest make oleic, palmitic, and stearic acids .

Once the oil is pressed from the seeds, the fibers are removed and the percentage of fatty acids rises.

The oil contains long-chain fatty alcohols, which also reduce inflammation, and two phytosterols: campesterol and beta-sitosterol .

How Does Evening Primrose Oil Work?

Evening primrose oil fights oxidative stress in tissues and increases the master antioxidant glutathione, mainly in heart and blood. Boosting glutathione protects the tissues in the body from stressors .

GLA and alcohols in evening primrose oil also block inflammatory pathways in the body, reducing inflammatory substances, enzymes, and cascades .



  • May improve rheumatoid arthritis
  • May help with skin disorders
  • May help prevent heart disease
  • May help with nerve damage
  • May help with blood sugar control
  • May improve dry eye


  • Insufficient evidence for most benefits
  • Not recommended in people with bleeding disorders or scheduled surgery
  • Not safe for pregnant women
  • May cause allergies
  • May interfere with blood thinners and lithium

Health Benefits

Rheumatoid Arthritis

No significant improvements in joint pain, stiffness, and swelling were observed in two 12-week clinical trials from the 1980s using evening primrose oil in 38 people .

However, another trial on 40 people found that evening primrose oil (6 g/day) mildly improved morning stiffness and joint pain .

More recently, evening primrose oil, fish oil (rich in EPA), and their combination reduced rheumatoid arthritis symptoms, painkiller use, and the risk of heart disease in 2 trials on 109 people .

Although no meta-analyses specific to evening primrose oil have been conducted, one on GLA concluded that it may reduce pain and disability in people suffering from rheumatoid arthritis .

Although the evidence is limited and includes trials with mixed results, it overall suggests that evening primrose oil may help with rheumatoid arthritis symptoms. You may discuss with your doctor if it may help as an add-on to your treatment regime.

Insufficient Evidence


Eczema is a very common chronic inflammatory skin condition that may require a combination of treatment approaches. Some researchers believe that a defect in the function of the enzyme delta-6-desaturase, which is responsible for the conversion of linoleic acid to GLA, may be a factor in the development of this condition .

Indeed, a study on 50 young adults with eczema found they had higher levels of cis-linoleic acid and GLA deficit. Supplementation with evening primrose oil corrected both this deficiency and eczema symptoms in this trial and 3 more on 56 adults and 24 children .

In line with this, a trial on 21 people correlated the increase in GLA with the effectiveness of the evening primrose oil treatment .

Oral evening primrose oil improved eczema symptoms such as inflammation, dryness, scaling, itching, redness, and overall sensitivity after 4-8 weeks in 6 clinical trials on 149 adults and 130 children and adolescents .

However, oral evening primrose oil (2-4 g in children and 6-8 g in adults) wasn’t more effective than placebo in 3 clinical trials on 285 people with eczema. Similarly, it was ineffective in another trial on 39 people with hand dermatitis .

In another trial on 24 people, topical evening primrose oil failed to prevent eczema caused by an ointment with the steroid betamethasone valerate .

The first meta-analysis conducted (in 1989) found evening primrose oil more effective than placebo at improving eczema symptoms, especially itching. However, one researcher pointed out that this meta-analysis was biased and included several non-peer reviewed studies while excluding a large trial with negative results .

An update of the previous meta-analysis that included 26 studies and over 1,200 people concluded that evening primrose oil had benefits on eczema symptoms but lost effectiveness with the use of potent steroids

The most recent meta-analysis on 27 studies and over 1,500 people (conducted by Cochrane) concluded that neither evening primrose nor borage oil were effective against eczema symptoms .

Because the results are mixed, we cannot conclude for certain that evening primrose oil (or any other sources of GLA) helps with eczema. More robust research is needed.

Skin Appearance

Evening primrose oil improved the overall appearance of the skin in a 12-week trial on 22 healthy adults. The oil increased skin moisture, elasticity, and firmness, while decreasing roughness .

A single, small clinical trial is insufficient to attest to the benefits of evening primrose oil for skin appearance. More clinical research is needed to confirm this preliminary finding.


In a 10-week study on 45 people with mild to moderate acne, a GLA supplement (borage oil) improved both inflammatory and non-inflammatory acne lesions .

GLA from hemp seed oil inhibited a microbe that causes acne (Propionibacterium acnes) in test tubes .

A small clinical trial and an antimicrobial study (both of which used GLA obtained from other sources than evening primrose oil) are clearly insufficient to support this potential benefit. More clinical trials using evening primrose oil are needed.

Skin Problems from Hemodialysis

People undergoing hemodialysis often have abnormal levels of blood fats and urea, which may cause skin problems with dryness, itching, and redness. In a small trial on 16 hemodialysis patients, oral evening primrose for 6 weeks improved these 3 symptoms. Larger, more robust clinical trials are needed to validate this preliminary result .

2) Preventing Heart Disease

Blood Fat Levels

High blood fats ( triglycerides and cholesterol) are one of the main risk factors for heart disease due to their potential to cause artery clogging. Platelets also play a role in artery clogging, since they bind to the blood vessel lining and recruit inflammatory cells.

In a trial from the 80s on insulin-dependent diabetics, evening primrose oil increased “good” HDL cholesterol levels and reduced the ability of the platelets to attach to the blood vessels .

Evening primrose oil supplementation lowered the blood levels of cholesterol (total and “bad” LDL cholesterol) and reduced platelet clumping in 2 clinical trials on 31 people with high blood fat levels, but was ineffective in 2 trials on 47 people with this condition .

More recently, evening primrose oil combined with vitamin D co-supplementation for 12 weeks improved blood triglycerides, and “bad” VLDL and LDL cholesterol in 2 clinical trials on 60 women with polycystic ovarian syndrome and 60 pregnant women with diabetes .

Evening primrose oil also reduced diet-induced artery clogging in mice .

Blood Clots

Thromboxanes constrict blood vessels, increase blood pressure, and increases clotting (platelet aggregation), while PGE1 helps relax blood vessels and increase blood flow. In a small trial on 7 non-insulin-dependent diabetics, a combination of evening primrose and fish oil lowered the ratio of thromboxanes to PGE1 .

Evening primrose oil has reduced platelet count and prevented them from clumping together in rabbits, rats, and mice .

To sum up, the effects of evening primrose oil on artery clogging have been tested in a few small trials with mixed results, in which those showing effectiveness often combined it with vitamin D. In turn, its effects on blood clot formation have been mainly tested in animals. The evidence is insufficient to back its role in protecting from heart disease until more clinical research sheds some light on this potential benefit.

3) Nerve Damage

In 2 clinical trials on over 100 diabetic people with nerve damage, taking 360 mg of GLA from evening primrose oil improved nerve function, especially in those with controlled blood sugar .

Evening primrose oil improved blood flow to the nerves and promoted their development while reducing their breakdown, resulting in an improved nerve function, in rats with nerve damage due to diabetes, high blood galactose, and crush injuries .

Although the results are promising, the evidence is insufficient to support the use of evening primrose oil in people with nerve damage. Larger, more robust clinical trials are needed to confirm these preliminary findings.

4) Diabetes

Evening primrose oil in combination with fish oil lowered fasting blood sugar in a small trial on 7 non-insulin-dependent diabetics. Its combination with vitamin D lowered fasting blood sugar and insulin while increasing insulin sensitivity in another trial on 60 women with diabetes caused by pregnancy .

Two small clinical trials cannot be considered sufficient evidence that evening primrose oil helps with blood sugar control in diabetics until more clinical research is carried out.

5) Dry Eye

In a clinical trial on 76 women, oral evening primrose oil improved eye dryness from contact lens use .

Oral GLA from borage oil or unspecified sources (combined with other fatty acids and artificial tears) improved eye dryness and inflammation in 3 trials on over 150 people with pink eye .

However, evening primrose oil was ineffective at treating dry eye caused by Sjogren’s syndrome (an autoimmune disease that mainly attacks the glands that produce tears and saliva) in a small trial on 28 people .

Because the results are mixed and most studies didn’t clearly specify that they used GLA from evening primrose or combined it with other fatty acids and artificial tears, there is insufficient evidence to support the use of evening primrose oil in people with dry eye. More clinical trials using evening primrose oil alone are needed to validate these preliminary results.

6) Raynaud’s Syndrome

Raynaud’s syndrome is a rare condition with episodes of reduced blood flow, especially to the fingers and toes. In a clinical trial on 21 people with this condition, evening primrose oil supplementation reduced the frequency and severity of the attacks, as well as platelet clumping .

A single, small clinical trial cannot be considered sufficient evidence that evening primrose oil improves Raynaud’s syndrome. Further clinical studies are needed.

7) Kidney Stones

Evening primrose oil (1 g/day for 20 days) decreased kidney stone risk factors (blood levels of calcium and oxalate) in a small trial of 16 people .

Again, this small clinical trial is clearly insufficient to support this potential use of evening primrose oil. More clinical research is required to validate this result.

8) Hot Flashes

Oral GLA from evening primrose oil wasn’t more effective than the placebo at reducing the frequency of hot flashes in a clinical trial on 35 menopausal women. However, it did reduce their severity in another trial on 56 women .

Further clinical research is warranted to shed some light on the potential effectiveness of evening primrose oil in women with hot flashes.

9) Multiple Sclerosis

An intervention with a special (“Hot-natured”) diet and evening primrose and hemp seed oil supplementation improved the fatty acid composition of red blood cells, overall symptoms and relapse rate, and the activity of liver and cell surface enzymes in a clinical trial on 100 people with multiple sclerosis .

However, evening primrose oil had no effect on platelet activity in a small trial on 14 people. In another trial on over 100 people, purified GLA (from an unspecified source) had no effect on the duration and severity of multiple sclerosis attacks .

Limited evidence suggests that evening primrose oil may have some positive effects when used in combination with another GLA source (hemp seed oil) and a special diet but not when used alone. However, we cannot conclude this for certain due to the small number of trials.

Possibly Ineffective

Five old clinical trials found evening primrose effective at improving PMS symptoms such as irritability, depression, breast tenderness, and fluid retention. However, a clinical trial on 38 women found it as effective as the placebo and a systematic review of 7 trials concluded that it was of little or no value in the management of PMS .

Evening primrose oil has been most widely studied regarding breast pain and tenderness. However, the results are mixed: while 3 clinical trials on over 250 women found it effective at reducing pain severity (especially if combined with vitamin E), 2 trials on almost 600 women found it as effective as the placebo .

Selective estrogen receptor modulators (centchroman) and topical non-steroidal anti-inflammatory drugs were clearly superior to evening primrose oil in 2 clinical trials on 160 women .

2) Asthma

Evening primrose oil (both alone and in combination with fish oil) was ineffective at improving asthma symptoms in 3 clinical trials on over 100 people .


An evening primrose oil supplement (Efamol) produced little or no effects on ADHD symptoms in 3 clinical trials on 67 children with this condition .

4) High Blood Pressure during Pregnancy (Pre-Eclampsia)

Evening primrose oil (both alone and combined with fish oil) had no preventive effect on pre-eclampsia in 2 clinical trials on almost 200 pregnant women .

5) Other Conditions

Evening primrose oil has only been evaluated in one clinical trial that produced negative results for the following conditions:

Side Effects & Precautions

This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects.

Call your doctor for medical advice about side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.

Evening primrose oil is generally safe when consumed at the recommended dosages. Some reported side effects include nausea, stomach pain, and headaches .

According to the Natural Standard Research Collaboration, allergy or hypersensitivity to oral evening primrose oil is uncommon but it may cause contact dermatitis .

A case report warned that its prolonged intake (for over one year) may cause inflammation, thrombosis, and immunosuppression .

Lipoid pneumonia is an underdiagnosed disease caused by the aspiration of lipid particles into the lungs. A 50-year-old woman developed this condition from using evening primrose oil in the long term. The condition improved when she stopped taking it .

Due to its potential blood-thinning effects, evening primrose oil should not be consumed by people with bleeding disorders or with a scheduled surgery.

Due to the lack of safety data, pregnant or breastfeeding women are advised to avoid evening primrose oil.

Drugs Interactions

Supplement/Herb/Nutrient-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.

Evening primrose oil may act as a blood thinner and add to the anticoagulant effects of medication such as warfarin .

For this same reason, it’s also important to be cautious and consult a doctor before combining evening primrose oil with other herbs that may increase bleeding time such as angelica, clove, danshen, garlic, ginger, ginkgo, red clover, and turmeric.

Evening primrose oil also has the potential to reduce serum lithium levels, so people on this medication (e.g., those with bipolar disorder) should consult their doctor before taking this oil .

Natural Sources and Forms of Supplementation

Evening primrose oil supplements have not been approved by the FDA for medical use due to the lack of solid clinical research. Regulations set manufacturing standards for supplements but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing with evening primrose oil.

Oral evening primrose oil is typically sold in capsules, tablets, and liquid solutions.

The oil can also be applied topically on the face, wounds, or skin regions with eczema and acne.

Because evening primrose oil is not approved by the FDA for any condition, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if evening primrose may be useful as a complementary approach in your case and which dose you should take.

The recommended daily dose of evening primrose oil is 4-5 capsules, tablets, or drops before or after each meal. Capsules and tablets typically contain 500 mg evening primrose oil .

User Experiences

The opinions expressed in this section are solely those of evening primrose oil users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfDecode. SelfDecode does not endorse any specific product, service, or treatment.

Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfDecode. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.

Users mainly used evening primrose oil for conditions such as chronic pain, skin health, hot flashes, and premenstrual symptoms. Several of the users were satisfied and reported dramatic improvements.

However, some users complained that the supplement didn’t work in their case. The adverse effects most commonly reported were mood swings and nausea.

What are the uses of primrose oil?

There are many potential uses for evening primrose oil, including the following:

Evening primrose oil for menopause and premenstrual syndrome

Share on PinterestEvening primrose oil has many therapeutic uses.

Hot flashes experienced by women going through the menopause have a number of non-hormonal treatment options, but, according to the evidence, evening primrose oil does not have an effect.

Some women report PMS symptoms being eased by evening primrose oil, for instance, breast tenderness, feelings of depression, irritability, and swelling and bloating from fluid retention.

However, there is no current evidence to support a role for evening primrose oil in easing premenstrual syndrome (PMS).

Evening primrose oil for nerve pain

Nerve pain associated with diabetes has been treated with evening primrose oil, when conventional treatments have not worked or have been unsuitable.

Beneficial results have been shown in clinical trials, and taking evening primrose oil for 6-12 months may improve the symptoms of nerve damage caused by diabetes.

In one small randomized trial published in Diabetic Medicine, for example, there was a statistically significant improvement in neuropathy scores, including nerve conduction tests, for people taking evening primrose oil capsules for 6 months compared with placebo.

Evening primrose oil for osteoporosis

Evening primrose oil is taken with fish oil and calcium by older adults with osteoporosis; the combination seems to decrease bone loss and increase bone density.

More research is needed to determine the role evening primrose oil itself might play independently of the other supplements.

Evening primrose oil for eczema

Share on PinterestEczema is sometimes treated with evening primrose oil

Treatment with oral evening primrose oil may help correct an abnormality in essential fatty acids found in eczema.

Eczema can be effectively treated with conventional medicines, but complementary alternatives, such as evening primrose oil are sometimes tried by people whose conditions do not improve as much as they would like, or who fear side effects.

However, a well-respected review of the evidence, conducted by the Cochrane Collaboration, concludes that evening primrose oil is no more effective than placebo at treating eczema, and can produce mild, temporary, mainly gastrointestinal side-effects.

Scleroderma and Raynaud’s phenomenon

Scleroderma is an autoimmune disease of the connective tissue characterized by thickening and hardening of various tissues, including the skin and other organs.

Raynaud’s phenomenon – which can cause the fingers to go numb and cold – is sometimes associated with scleroderma.

Evening primrose oil has been investigated as a treatment in a number of studies; however, all the studies so far have been small. Further research is needed before the oil can be recommended.

Evening primrose oil for other conditions

Herbal remedies tend to be associated with numerous health claims because the regulation of these products is less rigorous than for prescription drugs.

Many conditions are said to be eased by evening primrose oil. The following lack any supporting evidence:

  • asthma
  • ADHD
  • hepatitis B
  • high cholesterol
  • liver cancer
  • breast pain
  • obesity
  • psoriasis
  • psoriatic arthritis

The following conditions have “insufficient evidence” to support evening primrose oil as a treatment: chronic fatigue syndrome, diaper rash, dry eyes, dyslexia, dyspraxia, ichthyosis, infant development, pregnancy complications, rheumatoid arthritis, schizophrenia, Sjogren’s syndrome, ulcerative colitis, cancer, acne, multiple sclerosis, heart disease, and Alzheimer’s disease.

Evening Primrose Oil (evening primrose) Drug Interactions

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A total of 249 drugs are known to interact with Evening Primrose Oil (evening primrose).

  • 249 minor drug interactions

Show all medications in the database that may interact with Evening Primrose Oil (evening primrose).

Check for interactions

Type in a drug name to check for interactions with Evening Primrose Oil (evening primrose).

Most frequently checked interactions

View interaction reports for Evening Primrose Oil (evening primrose) and the medicines listed below.

  • biotin
  • biotin
  • black cohosh
  • black cohosh
  • Clomid (clomiphene)
  • Cod Liver Oil (multivitamin)
  • CoQ10 (ubiquinone)
  • Cymbalta (duloxetine)
  • Fish Oil (omega-3 polyunsaturated fatty acids)
  • folic acid
  • gabapentin
  • ibuprofen
  • levothyroxine
  • magnesium oxide
  • melatonin
  • metformin
  • multivitamin
  • multivitamin
  • omeprazole
  • Sleep (diphenhydramine)
  • Synthroid (levothyroxine)
  • tamoxifen
  • turmeric
  • Vitamin B12 (cyanocobalamin)
  • Vitamin C (ascorbic acid)
  • Vitamin D3 (cholecalciferol)
  • vitamin e
  • vitamin e
  • Vitamins (multivitamin)
  • Zoloft (sertraline)
  • Breastfeeding
  • Support Group
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  • 11 Reviews
  • Drug class: herbal products
  • Chronic Fatigue Syndrome
  • Diabetic Peripheral Neuropathy
  • Asthma
  • Eczema
  • … +7 more

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.


Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.


Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.


Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.


No interaction information available.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

Concerns raised about older adults mixing prescription drugs and herbal remedies

“One million over-65s could be suffering dangerous side effects from mixing ‘hazardous’ combinations of drugs and herbal remedies, study warns,” reports the Mail Online.

This follows a postal survey of 149 adults aged 65 and above from southeast England. The survey wanted to see whether people were choosing to take herbal or dietary supplements while also taking prescription medication. All respondents were taking at least 1 prescription drug, and a third of them were also taking some kind of supplement.

Most of the combinations were not harmful, but the researchers did find some people taking combinations that were potentially harmful.

These included:

  • a class of blood pressure drug (calcium channel blockers) with the herbal remedy St John’s wort, which may reduce the effectiveness of the blood pressure drug
  • the type 2 diabetes drug metformin with glucosamine, which may affect blood glucose control
  • another blood pressure medication bisoprolol with omega-3 fish oil, which may further reduce blood pressure

The study gives an indication of how common supplement use is, and in some cases raises concerning patterns. However, it was a very small study and it is difficult to know whether the results would generalise to the wider population. There may be other drug-supplement interactions that were not found in this small group, but which might exist in other populations.

Some people mistakenly think a treatment or supplement marketed as “herbal” means it does not cause any side effects or drug interactions.

If you are unsure whether it is safe to take a supplement with your prescribed medication, read the leaflets provided with both medicines, or talk to your pharmacist or GP.

It’s worth noting that these sorts of drug interactions can affect people of any age, not just people aged over 65.

Read more NHS advice about herbal remedies.

Where did the story come from?

This study was carried out by researchers from the University of Hertfordshire and NHS Improvement. The study did not receive any funding. It was published in the peer-reviewed British Journal of General Practice.

The UK media generally covered the story fairly well, although the headlines tended to focus on the estimate that more than a million people could be affected. This figure is uncertain as it was based on a very simple calculation scaling up from a small study.

Also, many of the papers used the phrase “alternative medicines”, when some of the substances studied in this research were actually commonly used food and vitamin supplements.

By talking about alternative medicines, people might not realise that this study is relevant to them, as they may have a different understanding of that phrase.

What kind of research was this?

This was a cross-sectional survey, which means that a group of people were studied at a single point in time. This kind of study has the benefit of being relatively simple and quick to carry out. It’s also a good way to look at how common something is (like use of herbal supplements) at a particular time.

However, cross-sectional studies can’t tell us much more than this or explore the reasons behind observed patterns. We don’t know the details of why people were taking drugs and supplements at the same time, for how long they had done this, and whether this had caused problems for them. Also, studies need to include a large and random cross-section of the relevant population to be able to give a reliable estimate of how common something is. So this small localised study may not be truly representative.

What did the research involve?

Between January and April 2016, this study mailed questionnaires to 400 older adults who were not living in care homes. Some were from a GP practice based in a rural area of Essex with a mainly white population. The others were from a GP practice in an area of London with a higher proportion of people from black, Asian and other minority ethnic groups.

Eligible participants were randomly selected people aged 65 or over who were taking at least 1 prescription medication. People with dementia, those who were terminally ill, and those who would not be able to consent to participate were excluded.

The questionnaire asked people what prescription drugs they were taking, as well as what “herbal medicinal products” or dietary supplements they might also be using. The questionnaire included examples of common herbal products (such as St John’s wort or gingko) so that people understood what might be included in that category.

The researchers used a database to check whether people were taking any combination of prescription medicine and herbal remedy known to be potentially harmful. They labelled each interaction according to the following criteria:

  • action: whether it needed action or not
  • severity: how likely it was to cause a problem for the patient if the situation was not managed
  • evidence: how good is the evidence around the interaction

Reminder letters were sent after 2 weeks, and further questionnaires were then sent to people who hadn’t previously responded. In total, 149 people responded and could be included in the analysis.

What were the basic results?

People were taking an average of 3 prescription drugs on a regular basis, with the most common including statins, beta-blockers and calcium channel blockers (used in the treatment of heart conditions and high blood pressure) and non-steroidal anti-inflammatory drugs (NSAIDs).

Around a third (33.6%) of the people in the study were using herbal remedies or supplements alongside their regular medications. This rate was higher in women (43.3%) than men (22.5%). People who were using herbal remedies or supplements were taking just 1 on average, though some people took as many as 8.

Most of the people (78%) who took supplements alongside their prescribed medication were taking vitamin and mineral supplements including cod liver oil, multivitamins, vitamin D and glucosamine.

They found 20% of people were using herbal products only. The most common were evening primrose oil, valerian, Nytol Herbal®, and garlic. Just over half of the reported potential interactions were considered to not be of clinical significance. However, 21 combinations were identified as having uncertain consequences, and 6 were considered potentially hazardous or significantly hazardous.

The combinations considered particularly risky were:

  • the supplement Bonecal with levothyroxine (medicine for an underactive thyroid); the calcium in Bonecal reduces the effectiveness of levothyroxine
  • peppermint taken with the medicine lansoprazole (which lowers stomach acid) – the medicine may affect the protective coating of peppermint capsules, which could lead to side effects caused by the peppermint
  • St John’s wort with the blood pressure drug amlodipine, which may make the drug less effective
  • the supplement glucosamine with metformin (a diabetes drug), a combination that may affect blood glucose control
  • omega-3 fish oil with the blood pressure drug bisoprolol, which can lower blood pressure too much
  • the herbal remedy gingko with the stomach acid drug rabeprazole – this makes the drug less effective

How did the researchers interpret the results?

The researchers noted that if their study was representative of the population as a whole, then potentially 1.3 million older adults in the UK might be at risk of at least 1 herb-drug or supplement-drug interaction. They suggest GPs should routinely question the use of herbals and supplements among older adults.


This study gives us an interesting snapshot into the habits of a group of older adults who are using supplements alongside their prescription medications.

But we don’t know how representative this study is of the wider population of older adults in the UK. The study includes patients from only 2 GP surgeries in southeast England. Although the researchers chose practices with different population characteristics, the people in the study might not be representative of the country as a whole.

The study was also very small, at just 149 people. We don’t know anything about the people who did not participate. For example, it may be that these people were more likely to be users of herbal remedies and didn’t want to share this information with their doctor. Or they might not have used herbal remedies at all and didn’t think the study was relevant to them. Either way, this could affect the results and mean the study is not representative.

Finally, the study did not explore the reasons why people were taking supplements or herbal products alongside prescribed drugs, for how long they had done this, and whether they were aware of potential interactions. We also don’t know whether there were any actual side effects or harms reported by the people in the study.

If you are unsure whether it is safe to take a herbal remedy or supplement along with your regular medication, talk to a pharmacist or your GP. It is also a good idea to do this if you are taking a lot of different medications that have been added to your prescription over the years, or if you are unsure what any of your medications are for.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

One million over-65s could be suffering dangerous side effects from mixing ‘hazardous’ combinations of drugs and herbal remedies, study warns

Mail Online, 25 September 2018

Alternative medicine use may put 1.3 million older people at risk, study suggests

The Independent, 25 September 2018

Millions of pensioners ‘at risk’ from alternative remedies as they ‘could react with their prescription drugs’

The Sun, 25 September 2018

Health supplements hinder drugs, elderly warned

The Times (subscription required), 25 September 2018

Links to the science

Agbabiaka TB, Spencer NH, Khanom S, Goodman C.

Prevalence of drug–herb and drug–supplement interactions in older adults: a cross-sectional survey

British Journal of General Practice. Published online September 24 2018

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