Vitamin a side effect

Vitamin A

What is vitamin A?

Vitamin A is a fat-soluble vitamin and an antioxidant that may help reduce the risk of cancer. Since the body stores fat-soluble vitamins, we do not need to consume them in large daily amounts like water-soluble vitamins.

Vitamin A comes in different forms. The vitamin A that we obtain from animal products is called retinoids. Vitamin A from retinoids is already in the form used by the body and is added to our stores right away.

Vitamin A found in fruits and vegetables is known as carotenoids, which need to be converted into retinoids before the body can use them.

Track Vitamin A with MyFoodDiary

How does the body use vitamin A?

Vitamin A is important to vision and bone growth. Night vision is highly dependent on vitamin A since it is used to form pigments that allow our eyes to adjust to changes in light. Vitamin A also plays a vital role in white blood cell production and the maintenance of several organs, including the heart, lungs, and kidneys.

How much vitamin A do I need in my diet?

The recommended daily allowance (RDA) of vitamin A is measured in retinol activity equivalents (RAE), which take into account the body’s ability to absorb various types of vitamin A. Retinol, a variety of retinoid, is used as the baseline since the body converts all vitamin A into retinol.

Quantity Equal to 1 mcg RAE
Vitamin A Type mcg
Retinol 1
Beta-carotene 12†
Alpha-carotene 24
Beta-cryptoxanthin 24

Source: National Institutes of Health1 † Some researchers suggestion 21 mcg of beta-carotene are needed to equal 1 mcg of retinol.2

Recommended Daily Allowances
Group RDA (mcg RAE)
Men 19+ 900†
Women 19+ 700
Pregnant Women 770‡
Lactating Women 1,300

Source: National Institutes of Health1 † Recommended daily value on new Nutrition Facts labels ‡ Pregnant women should not take high doses of vitamin A supplements or use topical retinoids, which have been linked to congenital disabilities.1

Nutrition Facts Label

Up until 2016, the US Department of Agriculture (USDA) required food manufacturers to list vitamin A on Nutrition Facts labels. The recommended daily value was 5,000 International Units (IU), which treated all sources of vitamin A as equal without regard to the body’s ability to absorb the nutrient. New Nutrition Facts labels no longer require vitamin A to be listed, but food manufacturers can voluntarily include it. The new recommended daily value is 900 mcg RAE.

What are good sources of vitamin A?

Vitamin A is found in animal products, fruits, and vegetables. Animal sources of vitamin A typically contain high dietary cholesterol levels since vitamin A is located in cholesterol storage tissues, like the liver. The best fruit and vegetable sources of vitamin A tend to be yellow, orange, and dark green. Many food products are also fortified with vitamin A.

Food Serving Size mcg RAE
Beef Liver 4 oz 5,614
Sweet Potato 1 medium 1,096
Pumpkin Pie 1 slice 596
Carrots 1/2 cup 534
Cooked Spinach 1/2 cup 472
Cantaloupe 1 cup 270
Pickled Herring 3 oz 219
Mango 1 fruit 181

Source: US Department of Agriculture3

What is Vitamin A deficiency?

Vitamin A deficiency (or hypovitaminosis A) is a condition caused by low levels of vitamin A in the body.


  • Night blindness
  • Slowed growth and bone development
  • Inadequate immune function
  • Increased infections


  • Insufficient vitamin A consumption
  • Low iron levels. Iron helps the body absorb and metabolize vitamin A.
  • Low zinc levels. Zinc helps vitamin A move from the liver to other parts of the body.
  • Excessive alcohol consumption
  • Liver problems
  • Intestinal diseases

Vitamin A toxicity (or hypervitaminosis A) is a condition caused by an excessive level of vitamin A in the body. Toxic levels of vitamin A can cause congenital disabilities, osteoporosis, liver problems, and central nervous system problems. Experts suggest men and women above the age of 19 should consume less than 3,000 mcg RAE of vitamin A per day to prevent toxicity.1

If reserves of vitamin A are at healthy levels, the body will not convert plant-based vitamin A (carotenoids) into the usable form (retinoids). On the other hand, the body will store animal-based retinoids regardless of the amount of vitamin A stored. As a result, vitamin A toxicity is usually caused by consuming excessive amounts of animal-based foods. Improper use of supplements can also lead to toxicity.

Additional Resources

  • Harvard School of Public Health: Vitamin A
  1. Vitamin A Fact Sheet. National Institutes of Health.
  2. West, CE, Eilander, A, & Lieshout, MV (2002). Consequences of Revised Estimates of Carotenoid Bioefficacy for Dietary Control of Vitamin A Deficiency in Developing Countries. The Journal of Nutrition, 132(9).
  3. Food Composition Databases. United States Department of Agriculture.

Vitamin A supplementation in infants and children 6–59 months of age

Guidance summary*

WHO recommendations

In settings where vitamin A deficiency is a public health problem** (prevalence of night blindness is 1% or higher in children 24–59 months of age or where the prevalence of vitamin A deficiency (serum retinol 0.70 µmol/l or lower) is 20% or higher in infants and children 6–59 months of age), high-dose vitamin A supplementation is recommended in infants and children 6–59 months of age.

Suggested vitamin A supplementation scheme for infants children 6–59 months of age
Target group Infants 6–11 months of age (including HIV+) Children 12–59 months of age (including HIV+)
Dose 100 000 IU (30 mg RE) vitamin A 200 000 IU (60 mg RE) vitamin A
Frequency Once Every 4-6 months
Route of administration Oral liquid, oil-based preparation of retinyl palmitate or retinyl acetatea
Settings Populations where the prevalence of night blindness is 1% or higher in children 24–59 months of age or where the prevalence of vitamin A deficiency (serum retinol 0.70 μmol/l or lower) is 20% or higher in infants and children 6–59 months of age

IU, intern ational units; RE, retinol equivalent.
a. An oil-based vitamin A solution can be delivered using soft gelatin capsules, as a single-dose dispenser or a graduated spoon (2). Consensus among manufacturers to use consistent colour coding for the different doses in soft gelatin capsules, namely red for the 200 000 IU capsules and blue for the 100 000 IU capsules, has led to much improved training and operational efficiencies in the field.


  • This guideline replaces previous recommendations on vitamin A supplementation for the prevention of vitamin A deficiency, xerophthalmia and nutritional blindness in infants and children 6–59 months of age (3).
  • The above recommendation can also be applied in populations where infants and children may be infected with HIV.
  • The magnitude of the effect may differ across settings and populations, possibly due to the extent of vitamin A deficiency or the availability of other nutrients (e.g. dietary intake of vitamin A will differ across locations and the effects of supplementation may be smaller in places with greater access to vitamin A-rich foods or with regular consumption of vitamin A-fortified foods).
  • This intervention should be used along with other strategies to improve vitamin A intakes, such as dietary diversification (4) and food fortification (5).
  • Adverse effects within 48 hours of receiving supplements containing 100 000–200 000 IU vitamin A are usually mild and transient, with no longterm consequences. Adverse effects may include bulging of open fontanelles in younger infants, and nausea and/or vomiting and headache in older children with closed fontanelles.
  • Vitamin A supplements should be delivered to children 6–59 months of age twice yearly, during health system contacts. This should be marked on the child health card, or integrated into other public health programmes aimed at improving child survival, such as polio or measles national immunization days, or biannual child health days delivering a package of interventions such as deworming, distribution of insecticide-treated mosquito nets and immunizations.
  • A quality assurance process should be established to guarantee that supplements are manufactured, packaged and stored in a controlled and uncontaminated environment (6).
  • When determining the vitamin A status of a population, guidelines on indicators for assessing vitamin A deficiency should be referred to (7, 8).
  • Recommendations for the treatment of xerophthalmia and the use of vitamin A supplements during episodes of measles are not covered in this guideline. Existing guidelines on the treatment of xerophthalmia and measles in infants and children 6–59 months of age should be referred to in these cases (3, 9).

* This is an extract from the relevant guideline (10). Additional guidance information can be found in this document.
** Determination of vitamin A deficiency as a public health problem involves estimating the prevalence of deficiency in a population by using specific biochemical and clinical indicators of vitamin A status. Classification of countries based on the most recent estimates is available in the guidance document, Global prevalence of vitamin A deficiency in populations at risk 1995–2005 (1).

1. WHO. Global prevalence of vitamin A deficiency in populations at risk 1995–2005. WHO Global Database on Vitamin A Deficiency. Geneva, World Health Organization; 2009 (

6. WHO, WHO Expert Committee on Specifications for Pharmaceutical Preparations. Quality assurance of pharmaceuticals: meeting a major public health challenge. Geneva, World Health Organization; 2007 (

7. WHO Indicators for assessing vitamin A deficiency and their application in monitoring and evaluating intervention programmes. Geneva, World Health Organization; 1996 (

8. WHO. Serum retinol concentrations for determining the prevalence of vitamin A deficiency in populations. Vitamin and Mineral Nutrition Information System. Geneva, World Health Organization; 2011 (

Vitamin A, or retinol, is a vitamin available over-the-counter OTC) as a nutritional supplement, or as the prescription injection Aquasol A when high doses are needed.

One of four fat-soluble vitamins (the others are vitamins D, K, and E), vitamin A is absorbed best when taken with food.

The liver stores as much as 90 percent of the body’s vitamin A.

Vitamin A comes in many different forms, which generally fall into two categories: preformed vitamin A in animal products like meat and dairy, and provitamin A in plants. (Provitamin A is converted to vitamin A in the body.)

Vitamin A-Rich Foods

Beta-carotene in vegetables such as carrots and sweet potatoes is the most common provitamin A.

Dairy products (such as cheese and fortified milk), eggs, cod, and halibut are rich sources of preformed vitamin A.

Organ meats, such as liver and kidney, contain large amounts of vitamin A, too.

Plant-based sources of provitamin vitamin A include pumpkin, broccoli, and dark green, leafy vegetables.

Unlike many animal sources of vitamin A, plant sources generally don’t contain saturated fat or cholesterol.

Vitamin A Deficiency

The World Health Organization (WHO) reports that vitamin A deficiency is the most common cause of preventable blindness in children worldwide.

A shortage of vitamin A also weakens a child’s immune system and increases the risk of certain infections (such as measles), diarrhea, and other conditions.

Pregnant women with low vitamin A levels are prone to night-blindness and run a greater risk of dying during pregnancy, especially during the last trimester or during childbirth.

Vitamin A Toxicity

Excess water-soluble vitamins are excreted in urine, but tissues store fat-soluble vitamins that aren’t used.

Consuming large amounts of vitamin A poses a health risk.

For instance, studies indicate that abnormally high levels of vitamin A in the blood suppress bone rebuilding, increase bone loss, and increase one’s risk for osteoporosis.

Symptoms of sudden vitamin A overdose include increased pressure in the space between the skull and the brain, nausea, stomach pain, vomiting, and skin peeling.

Signs of long-term vitamin A toxicity are coarse hair, thinning eyebrows, dry skin, cracked lips, weakness, and severe headache.

One major sign of vitamin A toxicity is carotenosis, a condition in which the palms of the hands and soles of the feet appear a deep yellow or orange color.

Vitamin A and Acne

Vitamin A promotes skin healing by stimulating the immune system and acting as an antioxidant to prevent skin cell damage.

The nutrient also helps regenerate skin tissue, aiding repair and encouraging new skin cell growth.

These features make prescription forms of vitamin A useful for acne treatment.

Vitamin A Warnings

You shouldn’t take vitamin A if you’re allergic to it or any other ingredient found in the supplement you’re taking.

People who already have symptoms of vitamin A toxicity should avoid the supplement.

Ask your doctor before taking vitamin A if you have:

  • Liver or kidney disease
  • Problems with alcohol abuse
  • Acne vulgaris
  • Conditions that affect your ability to absorb nutrients from food

Pregnancy and Vitamin A

Vitamin A is safe to take during pregnancy and breastfeeding as long as you don’t take more than the recommended amount for your age and condition.

High doses of vitamin A, however, may cause birth defects, miscarriages, and harm to your nursing baby.

Tell your doctor if you’re pregnant, planning a pregnancy, or are breastfeeding before taking a vitamin A supplement.

Are high amounts of vitamin A toxic?

Premium Insurance Caps contains beta-carotene, which is a precursor for vitamin A. However, it is not the same thing as fat-soluble vitamin A. Beta-carotene, which is virtually non-toxic (if not altogether non-toxic), is used make vitamin A in the body on an “as needed” basis. The only side effects that have been documented with extremely high doses of beta-carotene are diarrhea and a yellow-to-orange coloration to the hands and feet. These symptoms disappear upon cessation of beta carotene supplementation or lowering of the dose.

Regarding vitamin A toxicity, Dr. Shari Lieberman writes, “… can, therefore, be toxic in large amounts. In general, a normal healthy adult must take at least 100,000 IU of vitamin A daily for a period of months in order to display any signs of toxicity. Early signs of toxicity are fatigue, nausea, vomiting, headache, vertigo, blurred vision, muscular incoordination, and loss of body hair. Although all of these symptoms are reversible when vitamin A supplementation is stopped, I would not recommend this dose unless you are under professional guidance. Beta-carotene, on the other hand, can be given for long periods of time virtually without risk of toxicity.”

Dr. Michael Colgan says this about vitamin A:

“The medical literature contains about 600 cases of vitamin A poisoning. A lot of these cases have been with women given daily prescribed mega-doses of over 330,000 mcg RE (1,000,000 IS) of cis-retinoic acid for skin complains. Such mega-doses are especially dangerous because they build up in your body fat. World expert on the toxicity of nutrients, Dr. John Hathcock of Iowa State University and the Food and Drug Administration, concludes that toxicity of vitamin A does not occur for most people in normal health until they take a dose above 1,000 RE per kilogram bodyweight. That’s 70,000 mcg (230,000 IU) for a 70 kg (154 lb) athlete. He does cite some reports of headache, intracranial hypertension, and skin lesions in children and sick individuals at intakes of only 10,000 – 15,000 mcg RE, but none with normal adults. In any case, sensible supplementation does not even approach such figures. We have never found an athlete that needed more than 5,000 mcg RE (16,500 IU) per day.”

Again, we do not use “straight” vitamin A in Premium Insurance Caps (or any of our products), but instead use beta-carotene. 7-14 capsules of Premium Insurance Caps contain 12,500 – 25,000 IU of beta-carotene, which is the suggested Optimal Daily Intake (ODI). This amount, and perhaps even higher amounts, is fine because our body uses beta-carotene selectively to obtain however much vitamin A is needed, and discards what it does not need.

Surely you have heard the saying, “too much of a good thing can become a bad thing.” The same applies to vitamin supplements, as taking an excess of vitamins can be harmful to your health. This may seem contradictory because vitamins are often encouraged to supplement nutrients that may be lacking in our diets. Physicians or nutritionists may suggest vitamins once it is confirmed that you have a nutrient deficiency and highly advise that the daily recommended doses are followed.

The Institute of Medicine has established guidelines such as the RDA (Recommended Dietary Allowance) and DV (Daily Value) to help people understand the daily suggested dose of vitamins.

Vitamin overdose occurs when a person ingests far more than the daily recommendation, for an extended period of time. Although the body can excrete excessive amounts of water-soluble vitamins such as vitamin C, it can retain fat-soluble vitamins such as vitamin A, which can be toxic.

Here are a few vitamins that are proven to be toxic if taken in excess, as well as their symptoms of overdose:

  • Iron- Nausea, bloody stools, diarrhea, dizziness, headache, fluid build-up in the lungs and fever.
  • Vitamin A-Hair loss, liver damage, severe headaches, bone pain, blurred vision, dry skin and vomiting
  • Vitamin D- Abnormal heart rhythm, constipation, frequent urination, muscle weakness and confusion.
  • Vitamin E- Interferes with the body’s ability to clot blood, which can be harmful for those on blood thinning medication
  • B Vitamins-B6 in excess can cause nerve damage; while B3 can cause jaundice, elevated liver enzyme levels and nausea.

If you have decided to purchase vitamins, always follow the daily recommended dose to avoid excessive intake. Before purchasing it is recommended that you consult a physician or nutritionist to receive an assessment.

All content of this newsletter is intended for general information purposes only and is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. Please consult a medical professional before adopting any of the suggestions on this page. You must never disregard professional medical advice or delay seeking medical treatment based upon any content of this newsletter. PROMPTLY CONSULT YOUR PHYSICIAN OR CALL 911 IF YOU BELIEVE YOU HAVE A MEDICAL EMERGENCY.

Vitamin A (Retinol)

Alberts D, Ranger-Moore J, Einspahr J, et al. Safety and efficacy of dose-intensive oral vitamin A in subjects with sun-damaged skin. Clin Cancer Res. 2004;10:1875-1880.

Arora A, Willhite CA, Liebler DC. Interactions of beta-carotene and cigarette smoke in human bronchial epithelial cells. Carcinogenesis. 2001;22(8):1173-1178.

Bershad SV. The modern age of acne therapy: a review of current treatment options. Mt Sinai J Med. 2001;68(4-5):279-286.

Bjelakovic G, Nikolova D, Simonetti RG, Gluud C. Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis. Lancet. 2004;364:1219-1228.

Cumming RG, Mitchell P, Smith W. Diet and cataract: the Blue Mountains Eye Study.Ophthalmology. 2000;107(3):450-456.

French AL, Kirstein LM, Massad LS, et al. Association of vitamin A deficiency with cervical squamous intraepithelial lesions in human immunodeficiency virus-infected women. J Infect Dis. 2000;182(4):1084-1089.

Frieling UM, Schaumberg DA, Kupper TS, Muntwyler J, Hennekens CH. A randomized, 12-year primary-prevention trial of beta carotene supplementation for nonmelanoma skin cancer in the Physicians’ Health Study. Arch Dermatol. 2000;136(2):179-184.

Hall JA, Grainger JR, Spencer SP, Belkaid Y. The role of retinoic acid in tolerance and immunity. Immunity. 2011;35(1):13-22.

Kang S, Fisher GJ. Voorhees JJ. Photoaging: pathogenesis, prevention, and treatment. Clin Geriatr Med. 2001;17(4):643-659.

Kliegman. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011.

Jänne PA, Mayer RJ. Chemoprevention of colorectal cancer. N Engl J Med. 2000;342(26):1960-1968.

Michels KB, Giovannucci E, Joshipura KJ, et al. Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers. J Natl Cancer Inst. 2000;92:1740-1752.

National Institutes of Health, Office of Dietary Supplements. Facts About Dietary Supplements: Vitamin A and Carotenoids. December 2001.

Patrick L. Beta-carotene: the controversy continues. Altern Med Rev. 2000;5(6):530-545.

Patrick L. Nutrients and HIV:Part 2 — vitamins A and E, zinc, B-vitamins, and magnesium. Altern Med Rev. 2000;5(1):39-51.

Rai SK, Nakanishi M, Upadhyay MP, et al. Effect of intestinal helminth infection on retinol and beta-carotene status among rural Nepalese. Nutr Res. 2000;20(1):15-23.

Ribaya-Mercado JD, Blumber JB. Vitamin A: is it a risk factor for osteoporosis and bone fracture? Nutr Rev. 2007;65(10):425-438.

Rock CL, Michael CW, Reynolds RK, Ruffin MT. Prevention of cervix cancer. Crit Rev Oncol Hematol. 2000;33(3):169-185.

SanGiovanni JP, Chew EY, Clemons TE, Ferris FL, Gensler G, Lindblad AS, Milton RC, Seddon JM, Sperduto RD. The relationship between dietary carotenoid and vitamin A, E and C intake with age-related macular degeneration in a case-control study. Report No. 22. Arch Ophthalmol. 2007;125(9):1225-1232.

Sei H. Vitamin A and sleep regulation. J Med Invest. 2008;55(1-2):1-8.

Sommer A, Vyas K. A global clinical view on vitamin A and carotenoids. Am J Clin Nutr. 2012;96(5):1204S-62.

Sorg O, Saurat JH. Topical retinoids in skin ageing: a focused update with reference to sun-induced epidermal vitamin A deficiency. Dermatology. 2014;228(4):314-25.

Stratton SP, Dorr RT, Alberts DS. The state-of-the art in chemoprevention of skin cancer. Eur J Cancer. 2000;36(10):1292-1297.

Tafti M, Ghyselinck NB. Functional implication of the vitamin A signaling pathway in the brain. Arch Neurol. 2007;64(12):1706-1711.

Thornquist MD, Kristal AR, Patterson RE, et al. Olestra consumption does not predict serum concentrations of carotenoids and fat-soluble vitamins in free-living humans: early results from the sentinel site of the olestra post-marketing surveillance study. J Nutr. 2000;130(7):1711-1718.

van Zandwijk N, Dalesio O, Pastorino U, de Vries N, van Tinteren H. EUROSCAN, a randomized trial of vitamin A and N-acetylcysteine in patients with head and neck cancer or lung cancer. For the European Organization for Research and Treatment of Cancer Head and Neck and Lung Cancer Cooperative Groups. J Natl Cancer Inst. 2000;92(12):959-960.

Vetrugno M, Maino A, Cardia G, et al. A randomised, double masked, clinical trial of high dose vitamin A and vitamin E supplementation after photorefractive keratectomy. Br J Ophthalmol. 2001;85(5):537-539.

Villamor E, Fawzi WW. Vitamin A supplementation: implications for morbidity and mortality in children. J Infect Dis. 2000;182 Suppl 1:S122-S133.

Zhang YP, Chu RX, Liu H. Vitamin A intake and risk of melanoma: a meta-analysis. PLoS One. 2014;9(7):e102527.

Zouboulis CC. Retinoids — which dermatological indications will benefit in the near future? Skin Pharmacol Appl Skin Physiol. 2001;14(5):303-315.

Vitamin A

Vitamins and minerals

What does the Department of Health and Social Care advise?

You should be able to get all the vitamin A you need by eating a varied and balanced diet.

If you take a supplement that contains vitamin A, don’t take too much because this could be harmful.

Liver is a very rich source of vitamin A. Don’t eat liver or liver products, such as pâté, more than once a week.

You should also be aware of how much vitamin A there is in any supplements you take.

If you’re pregnant or thinking of having a baby:

  • avoid taking supplements containing vitamin A, including fish liver oil, unless advised to by your GP
  • avoid liver or liver products, such as pâté, as these are very high in vitamin A

Women who have been through the menopause and older men, who are more at risk of osteoporosis, should avoid having more than 1.5mg of vitamin A a day from food and supplements.

This means:

  • not eating liver or liver products, such as pâté, more than once a week, or having smaller portions of these
  • taking no more than 1.5mg of vitamin A a day in supplements (including fish liver oil) if you don’t eat liver or liver products
  • not taking any supplements containing vitamin A (including fish liver oil) if you eat liver once a week

Having an average of 1.5mg a day or less of vitamin A from diet and supplements combined is unlikely to cause any harm.

Vitamin A toxicity

What is vitamin A toxicity?

Vitamin A is a fat soluble retinoid. It also called retinol. Vitamin A is needed for immunity, visual and dermatological health as well as cell communication and growth. In excessive amounts, however, it can accumulate in the liver and cause a wide array of symptoms. Toxicity is classified as either acute or chronic.

Vitamin A toxicity is also known as hypervitaminosis A.

What causes vitamin A toxicity?

Acute toxicity

The most common cause of acute vitamin A toxicity is the ingestion (generally accidental) of over 300,000 IU of vitamin A.

Chronic toxicity

The most common cause of chronic vitamin A toxicity is the regular ingestion of over 100,000 IU daily, which is sometimes prescribed for dermatological conditions such as acne.

What are the signs and symptoms of vitamin A toxicity?

Signs and symptoms of acute vitamin A toxicity can include:

  • Gastrointestinal: nausea, vomiting, loss of appetite, abdominal pain
  • Neurological: dizziness, irritability, drowsiness, increased intercranial pressure due to cerebral oedema, and headache
  • Dermatological: rash or desquamation (peeling skin)
  • Coma and death

Signs and symptoms of chronic vitamin A toxicity can include:

  • Gastrointestinal symptoms: hepatomegaly, splenomegaly
  • Neurological symptoms: severe headache, pseudotumour cerebri
  • Dermatological symptoms: rash, thin and coarse hair, alopecia of the eyebrows, itch, skin that is dry, rough or cracking, and dry or cracked lips
  • Musculoskeletal: weakness, cortical hyperostosis of the bone, arthralgia, easy fractures

In children, signs and symptoms of vitamin A toxicity are:

  • Neurological: irritability, drowsiness, delirium, coma, increased intercranial pressure, bulging fontanelles (in infants), psychiatric changes, cerebral oedema
  • Ophthamological: bulging eyeballs, swelling of the cortical disc, visual disturbances
  • Dermatological: skin discoloration and/or desquamation, itch

It is also important to note that vitamin A is highly teratogenic if taken during pregnancy (especially in the first 8 weeks) if intake exceeds 10,000 IU daily. Birth defects can also be caused by isotretinoin or other oral retinoids, if taken while pregnant.

Vitamin A and teratogenicity

Excessive intake of Vitamin A during pregnancy has been associated with the following birth defects, collectively known as retinoic acid syndrome:

  • Encephalitis
  • Microcephaly
  • Craniofacial malformations (most commonly a cleft palate)
  • Cardiovascular malformations (most commonly a transposition of the great vessels)
  • Thymus malformation/dysfunction

How is vitamin A toxicity diagnosed?

Diagnosis of vitamin A toxicity is based on signs and symptoms, patient history, lifestyle habits and use of supplements. There is sometimes a poor correspondence between toxicity and serum retinol levels. However, serum levels can sometimes be between 1,000 and 20,000 (with a normal range being 200 to 800 µg/L). The blood sample must be protected from light.

How is vitamin A toxicity treated?

Vitamin a toxicity is treated by stopping the use of vitamin A supplements. Generally, signs and symptoms will resolve on their own with 1–4 weeks, depending on their severity. Birth defects caused by vitamin A toxicity during pregnancy are irreversible.

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