Kava kava drug interactions

Kava is a plant traditionally used as an intoxicating beverage by the indigenous people of the South Pacific. Kava can also be used to help with anxiety, stress, insomnia, and other disorders. However, high doses of kava may cause liver damage and the plant should not be taken in combination with alcohol or other psychotropic medications. Read on to learn more about the potential health benefits and side effects of kava.

What Is Kava?

Kava (Piper methysticum) extract is traditionally prepared from a combination of kava root and water and is commonly used as a psychotropic beverage in the South Pacific.

Forms of kava products include :

  • Root extract
  • Root capsules
  • Tincture
  • Root powder
  • Root tea
  • Concentrate paste

Kava tea, kava root extract, and capsules generally produce mild effects, while tinctures and powders are stronger. Kava paste produces the strongest effects, since the product is highly concentrated.

Importantly, several cases of liver damage and even death from taking kava (possibly due to the presence of the root and stem peelings in the kava product, instead of only the peeled root) have been reported. For this reason and its potential for abuse, kava is banned in Europe, the UK, and Canada .

Kavalpyrones and chalcones are the two main active compound classes of kava extract :

  • Kavalpyrones (methysticin, dihydromethysticin, yangonin, dihydrokavain, and kavain) produce muscular relaxation and calming effect.
  • Chalcones (flavokawain A, B, and C) have potential antioxidant, anti-inflammatory, antimicrobial, and anticancer effects.

Mechanisms of Action

Kavain and methysticin block sodium ion channels, leading to a decrease in cell excitability. By blocking sodium channels, kavain also reduces excitatory neurotransmitter release. Kavain and methysticin decrease stimulatory pathways, possibly leading to a calming effect .

Yangonin, kavain, dihydrokavain, methysticin, dihydromethysticin, and kava pyrones increase GABA in the brain (hippocampus, amygdala, and medulla oblongata). When GABA-A receptors are activated, neurons are inhibited, which may have sedative and anti-anxiety effects .

Multiple kavalactones (desmethoxyyangonin, methysticin, yangonin, dihydromethysticin, dihydrokavain, and kavain) inhibit monoamine oxidase B. Kavalactones prevent the enzyme MAOB from removing neurotransmitters norepinephrine, serotonin, and dopamine from the brain .

Kavain, desmethoxyyangonin, and methysticin increase noradrenaline, serotonin, and dopamine. Low levels of noradrenaline, serotonin, and dopamine are associated with depression, anxiety, ADHD, and other disorders .



  • May reduce anxiety
  • May improve sleep disorders and depression
  • May improve mood symptoms associated with menopause


  • Insufficient evidence for many benefits
  • Several cases of liver damage and even death reported
  • High potential for abuse
  • Banned in several countries
  • High risk of drug interactions

Health Benefits

Likely Effective for:

Multiple human studies showed that kava improved anxiety, regardless of the symptoms and type of disorder (nonspecific anxiety, tension, agitation, agoraphobia, specific phobia, or general anxiety disorder) .

In a clinical trial on 129 people with generalized anxiety disorder, kava extract (400 mg) was as effective as two anti-anxiety drugs (opipramol 10 mg and buspirone 100 mg) .

Kava activates GABA-A receptors, which produces a calming effect. Kava prevents a decrease in norepinephrine, serotonin, and dopamine levels by inhibiting monoamine oxidase and relaxes muscles by decreasing beta adrenaline receptor activity .

All in all, the evidence suggests that kava may help with anxiety. Remember that this supplement is not approved by the FDA for this purpose and is even banned in some countries due to its potential for abuse and risk of liver damage. Discuss with your doctor if it may be helpful in your case and always take it as recommended by them.

Insufficient Evidence for:

Kava reduced stress and improved sleep quality in 24 patients suffering from stress-induced insomnia. 61 patients suffering from sleep disturbances associated with anxiety, tension, and restlessness were also effectively treated with kava extract .

Kava’s potentially sedative effects are due to the blocking of sodium and calcium ion channels, increased neurotransmitter binding to GABA-A receptors, inhibition of monoamine oxidase B, and an increase of the neurotransmitters noradrenaline and dopamine .

Although promising, the evidence to support the use of kava in sleep disorders is insufficient. More clinical trials on larger populations are needed to confirm these preliminary results.

2) Depression

In a clinical trial on 60 people with generalized anxiety disorder, oral kava extract (250 mg kavalactones per day) reduced both anxiety and depressive symptoms .

Its combination with Saint John’s wort improved depression (but not anxiety or quality of life) in a small trial on 28 people with major depressive disorder .

Kava induced a pleasant mental state while reducing fatigue and anxiety in human and animal studies. Kavalactones in kava increased dopamine, serotonin, GABA (only slightly), and decreased glutamate in cell models .

Again, the results are promising but only two small clinical trials have been conducted. Further clinical research is required to confirm the potential benefits of kava in people with depression.

3) Menopausal Symptoms

Perimenopause and menopause symptoms include hot flashes, night sweats, insomnia, and increased anxiety and irritability.

Kava improved anxiety, depression, irritability, and insomnia in 3 clinical trials on 120 perimenopausal and menopausal women. It activated GABA-A receptors, inhibited monoamine oxidase-B, and increased dopamine levels in the brain .

All in all, there is insufficient evidence to claim that kava helps with mood symptoms of menopause and perimenopause. Larger, more robust clinical trials are needed to validate these findings.

4) Brain Function

A single dose of kava extract (300 mg) improved accuracy and performance in attention, visual processing, and working memory tasks in a small trial on 20 people .

In another trial on 12 people, kava extract (200 mg, 3x/day) slightly improved performance in a word recognition task .

Kava pyrones are active in parts of the brain (amygdala, caudate nucleus, and hippocampus) that deal with emotions and brain processes. However, chronic usage and higher doses of kava can result in impaired motor function .

Because only two, very small clinical trials have been conducted, there is insufficient evidence to support the use of kava as a cognitive enhancer. Further clinical research is needed.

5) Treatment of Drug Addiction

Kava reduced the cravings for addictive drugs in drug-dependent patients in a pilot study .

The anti-craving effects of kava are due to dopamine-producing neurons in the reward system of the brain (nucleus accumbens). The kava pyrone desmethoxyyangonin may increase dopamine .

A single pilot study (which we couldn’t access for a critical analysis) is clearly insufficient to back the potential benefits of kava in treating drug addiction. More clinical research is required.

Animal and Cell Research (Lack of Evidence)

No clinical evidence supports the use of kava for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.

Brain Protection

Kavalactones extracted from kava prevented brain damage caused by oxidative stress in brain disorders like Parkinson’s and Alzheimer’s disease in mice and cell studies. Kavalactones activate the Nrf2 antioxidant response pathway and increase the concentration of antioxidant enzymes (heme oxygenase-1), which may combat oxidative stress .

Epilepsy and Seizures

Kava helped treat seizures and epilepsy in rats. Alone and in combination with the antiepileptic drug diazepam, kava reduced motor activity, increased the seizure threshold, and enhanced the anticonvulsant effect of diazepam.

Kava binds to GABA-A receptors in the brain (hippocampus and frontal cortex) and blocks sodium and calcium ion channels in the brain .


In cell-based studies, kavain and flavokawains A and B inhibited NF-kB and decreased TNF-alpha, both of which play a central role in inflammation .

Immunity Boost

In mice, flavokawains A and B stimulated white blood cells in the spleen, causing the secretion of cytokines IL-2 and TNF-alpha and increasing the level of immune T cells .


Below, we will discuss some preliminary research on kava’s potential anticancer effects. It’s still in the animal and cell stage and further clinical studies have yet to determine if its extract may be useful in cancer therapies.

Do not under any circumstances attempt to replace conventional cancer therapies with kava or any other supplements. If you want to use it as a supportive measure, talk to your doctor to avoid any unexpected interactions.

Kava stopped the progression of bladder cancer and suppressed tumor growth in mice. Flavokawain A activated pathways (caspase-3/9 and Bax protein) that induce tumor cell death and inhibited proteins that prevent cell death (survivin) .

Flavokawain B reduced prostate tumor growth, in part by reducing androgen receptors in prostate cells, in both mice and cell studies. Flavokawain B also killed tumor cells by activating the pathways that cause cell death (caspases and Bax) .

Kava decreased breast cancer cell size, prevented their spreading, and increased their death. Flavokawain A, B, and a flavokawain derivative (FLS) increased the concentration of a protein that activates cell death (Bax) and inhibited two proteins needed for cell growth (PLK1 and FOXM1). Flavokawain A also cut off nutrient supply to tumors by inhibiting blood vessel formation and decreasing the levels of the glucose transporter GLUT1 .

Flavokawain B also inhibited the growth of colon cancer cells (through the release of cytochrome c and Bax/Bak protein) .

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.

Common side effects of kava consumption include headaches, dizziness, drowsiness, fatigue, depression, mild stomach discomfort, and diarrhea. Heavy and frequent use of kava can cause dry eye and dry scaling skin (dermopathy). These side effects are reversible with reduced intake or cessation .

Although kava is generally safe to use, using kava supplements containing stems, leaves, and root peelings can cause liver toxicity and damage. It is recommended to use extracts made from peeled kava rhizomes and roots.

Kava is not recommended as the primary agent for anxiety treatment. Avoid using kava in combination with alcohol to prevent liver damage .

Driving and operating heavy machinery is not recommended after consuming kava since kava may impair reaction time and motor skills .

Kava can be used recreationally as a psychoactive beverage and has the potential for drug abuse. Drinking kava produces hypnotic, narcotic, and muscle-relaxant effects, which are similar to the effects of alcohol consumption .

There have been a few reported cases of kava consumption leading to hepatitis A (a virus transmitted through contaminated water) infection in the liver .

Gene and Drug Interactions

Liver toxicity can be caused by an inability to break down kavalactones by cytochrome P450 enzymes CYP3A4 and CYP2D6 .

79% of the white population have a CYP2D6 deficiency and break down drugs at a slower rate. Interestingly, only 1% of Asians have CYP2D6 deficiency .

Whole kava extract inhibits cytochrome P450 enzymes (CYP1A2, CYP2C9, CYP2D6, CYP3A4, and CYP4A11), which break down many medications .

Common drugs that are broken down by CYP450 enzymes include:

  • Diazepam
  • Caffeine
  • Amitriptyline
  • Imipramine
  • Propranolol
  • Fluoxetine
  • Haloperidol
  • Morphine
  • Beta-blockers

Taking these medications in combination with kava could alter the effects of the medication, making it necessary to change the dosage. Always consult your doctor before supplementing with kava, especially if you are on a prescription medication .



Because kava 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 kava may be useful as a complementary approach in your case and which dose you should take.

The recommended dose of kava for medicinal use is 6 grams per day in tablet form.

People using it for recreational purposes often take much higher doses, as much as 50-200 g/day of powdered extract .

User Reviews

The opinions expressed in this section are solely those of kava 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.

According to most users, kava root extract capsules provided excellent anxiety and stress relief and function well as a sleep aid. However, some people found that the effects were not strong enough to reduce anxiety and stress.

Some users preferred kava instant mix. They reported immediate effects lasting for around an hour. However, many of them warned that its strong taste is not for everyone.

Some users experienced a reverse tolerance after consuming kava or complained that it took too long (up to 3 weeks) until the full effects kicked in.


Generic Name: kava (KA vah)
Brand Name:

Medically reviewed by Drugs.com on Sep 23, 2019 – Written by Cerner Multum

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What is kava?

Kava has been used in alternative medicine as a possibly effective aid in treating anxiety.

Other uses not proven with research have included cancer prevention, insomnia, depression, attention deficit disorder, preventing sedative withdrawal symptoms (from medicines such as Valium, Xanax, or Tranzene), and other conditions.

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

Kava 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.

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

Important Information

Kava is considered unsafe due to many reports of fatal effects on the liver, including hepatitis, cirrhosis, and liver failure.

You should not use kava if you have liver disease.

Before taking this medicine

Kava is considered unsafe due to many reports of fatal effects on the liver, including hepatitis, cirrhosis, and liver failure. Even short-term use (1 to 3 months) may increase your risk of liver damage.

You should not use kava if you have liver disease.

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

  • depression (especially if you take an antidepressant).

You should not take kava if you are pregnant. Kava may cause weaken muscle tone in the uterus.

Kava can pass into breast milk and may harm a nursing baby. You should not breast-feed while using kava.

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

How should I take kava?

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 kava, 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 forms (tablets, liquid, tincture, teas, etc) of kava at the same time without medical advice. Using different formulations together increases the risk of an overdose.

You should have frequent blood tests to check your liver function if you choose to take kava.

If you need surgery, stop taking kava at least 2 weeks ahead of time.

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

Store kava as directed on the package. In general, kava should be protected from light and moisture and stored in a sealed container.

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 kava 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.

Long-term use of kava can cause dry, flaking, discolored skin; reddened eyes; a scaly skin rash; puffy face; muscle weakness; blood abnormalities; and feelings of poor health.

What should I avoid while taking kava?

kava may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Avoid using kava together with other herbal/health supplements that can also harm the liver. This includes androstenedione, chaparral, comfrey, DHEA, germander, niacin (vitamin B3), pennyroyal oil, red yeast, and others.

Avoid drinking alcohol while taking kava. Alcohol may increase your risk of liver damage.

Avoid using kava with other herbal/health supplements that can also cause drowsiness. This includes 5-HTP (5-hydroxytryptophan), calamus, California poppy, catnip, gotu kola, Jamaican dogwood, melatonin, St. John’s wort, skullcap (or scullcap), valerian, yerba mansa, and others.

Kava side effects

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

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

Long-term use of kava may cause serious health problems, including:

  • dry, scaly, flaky skin;

  • yellowed skin, hair, fingernails, or toenails;

  • red eyes, puffy face;

  • decreased ability to absorb protein;

  • weight loss;

  • lung problems;

  • blood in your urine; or

  • blood cell disorders that can make it easier for you to bleed or get sick.

Common side effects may include:

  • drowsiness.

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 kava?

Taking kava with other drugs that make you sleepy can worsen this effect. Avoid taking kava together with a sleeping pill or sedative, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Do not take kava without medical advice if you are using a medication to treat any of the following conditions:

  • any type of infection (including HIV, malaria, or tuberculosis);

  • anxiety or depression;

  • arthritis pain, occasional pain, or tension headaches;

  • asthma or allergies;

  • cancer;

  • diabetes;

  • erectile dysfunction;

  • heartburn or gastroesophageal reflux disease (GERD);

  • high blood pressure, high cholesterol, or a heart condition;

  • migraine headaches;

  • psoriasis, rheumatoid arthritis, or other autoimmune disorders;

  • a psychiatric disorder; or

  • seizures.

This list is not complete. Other drugs may interact with kava, 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.

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Approximately 40 million American adults suffer from some form of anxiety disorder, according to the Anxiety and Depression Association of America. These disorders include generalized anxiety, panic disorders, social anxiety, specific phobias, obsessive-compulsive disorders and post-traumatic stress. At these rates, anxiety disorders are the most common mental health issues in the United States. Many people with anxiety disorders have other conditions as well, such as depression, Attention Deficit Hyperactivity Disorder (ADHD) and eating disorders.1

While conventional therapies and benzodiazepine medications such as Alprazolam (Xanax) or Clonazepam (Klonopin) are most often recommended for anxiety and related disorders, there is growing interest in complementary and alternative approaches to mental health care. Many people are increasingly searching for natural remedies for anxiety.

Among those that show promise for treating mild to moderate and generalized anxiety is the botanical supplement known as kava or kava-kava.

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What is Kava?

Kava originates from the root of a plant indigenous to South Pacific areas of the world, where it is used to make a popular beverage drunk socially and ritualistically during religious ceremonies. Researchers have tooled out a number of active ingredients found in kava, including kavalactones, kavapyrones, kawains, flavokawains, and others. These compounds are continuously being studied for their safety and effectiveness in treating a variety of mental and physical health conditions.

What is an Appropriate Dose?

But how do you know what an appropriate dose is when it comes to using kava for anxiety? While numerous science-based studies have proven kava’s effectiveness at reducing symptoms of anxiety and related conditions, they all used different doses of different formulas and preparations, expressed in different ways. For instance, after three weeks, at a dose of 250 mg kavalactones a day, given as five supplemental tablets daily for three weeks, kava significantly improved anxiety and depression in 60 adult study participants who had experienced generalized anxiety or anxiety accompanied by symptoms depression for at least one month.

But other studies have reported significant improvement of anxiety symptoms from 50 mg a day of dry extract standardized to 35 mg kavalactones, 90-110 mg dry kava extract standardized to 70 mg kavalactones, 150 mg a day special kava extract standardized to 35 mg kavalactones, 280 mg a day standardized to 30% kavalactones, and 400 mg a day standardized to 30% kavapyrones.2,3 While there is no official recommendation for kava dosage, the American Botanical Council advises 60 to 120 mg of kavapyrones (or kavalactones) as a safe and potentially effective range for no longer than three months, unless otherwise prescribed and taken under medical supervision.4

Forms of Kava

Various forms and strengths of kava are sold on the internet and in health food stores, including loose powders and tea bags used to make warm drinks, liquid extract added to water and other cool beverages, and capsules that are taken as dietary supplements. If you find yourself in New York’s East Village, you can visit the city’s first kava bar, where bartenders serve up bowls of kava garnished with a slice of pineapple. Since there are no official dose recommendations for using kava for anxiety, and different brands, forms, and batches contain different amounts of active ingredients, the product you select may or may not be effective for your purposes.

Before taking any over-the-counter kava preparations, speak with your primary or mental health care provider. Generally, kava is considered safe for short-term use but there are concerns about its long-term use and effectiveness. Kava has sedative qualities and may impair motor skills at high doses, especially in combination with other sedating drugs.

Potential Concerns

“Our concern about using kava supplements is related to the ways they may interact in medicated and/or highly sensitive patients,” says health psychologist David Bresler, Ph.D., LAc, founder of The Bresler Center in Los Angeles. “Individual differences in sensitivity can be huge, and while one patient may be completely unaffected by 40 mg of an anti-anxiety medication, another will drop quickly into sleep by taking just 0.25 mg of the same medication.”

As Dr. Bresler is keen to point out, much more research is necessary before the benefits and potential dangers of kava are completely understood. If you would like to try kava, a health professional who is knowledgeable about alternative and complementary medicines can give you advice and help you choose a product and dose that’s right for you. Recommended doses should be based on the type of kava taken, as well as individual factors such as age, weight, clinical diagnosis, and other drugs or supplements taken.

Article Sources Last Updated: Dec 4, 2019

Topic Overview

Kava—or kava kava—is a root found on South Pacific islands. Islanders have used kava as medicine and in ceremonies for centuries.

Kava has a calming effect, producing brain wave changes similar to changes that occur with calming medicines such as diazepam (Valium, for example). Kava also can prevent convulsions and relax muscles. Although kava is not habit-forming, its effect may decrease with use.

Traditionally prepared as a tea, kava root is also available as a dietary supplement in powder and tincture (extract in alcohol) forms.

What is kava used for?

Kava’s calming effect may relieve anxiety, restlessness, sleeplessness, and stress-related symptoms such as muscle tension or spasm. Kava may also relieve pain.

When taken for anxiety or stress, kava does not interfere with mental sharpness. When taken for sleep problems, kava promotes deep sleep without affecting restful REM sleep.

Kava may be used instead of prescription antianxiety drugs, such as benzodiazepines and tricyclic antidepressants. Kava should never be taken with these prescription drugs. Avoid using alcohol when taking kava.

Is kava safe?

Kava may have severe side effects and should not be used by everyone. Kava has caused liver failure in previously healthy people. You should not use kava for longer than 3 months without consulting your doctor.

Before you use kava, consider that it:

  • Should not be combined with alcohol or psychotropic medicines. Psychotropic medicines are used to treat psychiatric disorders or illnesses and include antidepressants and mood stabilizers. Alcohol exaggerates kava’s sedating effect.
  • Can affect how fast you react, making it unsafe to drive or use heavy machinery.
  • May gradually be less powerful as you use it.
  • Eventually may cause temporary yellowing of skin, hair, and nails.
  • Can cause an allergic skin reaction (rare).

Long-term kava use may result in:

  • Liver problems.
  • Shortness of breath (reversible).
  • Scaly rash (reversible).
  • Facial puffiness or swelling (reversible).

The U.S. Food and Drug Administration (FDA) has investigated whether using dietary supplements containing kava is associated with liver illness. Reports from Germany and Switzerland about kava causing serious liver problems have led to the recent removal of these products from shelves in Britain. Other countries have advised consumers to avoid using kava until further information is available.

In the United States, the FDA advises people who have liver disease or liver problems, or people who are taking medicines that can affect the liver, to consult a doctor or pharmacist before using products that contain kava. People who use a dietary supplement that contains kava and experience signs of illness should consult a doctor. Symptoms of serious liver disease include brown urine as well as yellowing of the skin or of the whites of the eyes. Other symptoms of liver disease may include nausea, vomiting, light-colored stools, unusual tiredness, weakness, stomach or abdominal pain, and loss of appetite.

The FDA does not regulate dietary supplements in the same way it regulates medicine. A dietary supplement can be sold with limited or no research on how well it works.

Always tell your doctor if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a dietary supplement. This is especially important for women who are pregnant or breastfeeding.

When using dietary supplements, keep in mind the following:

  • Like conventional medicines, dietary supplements may cause side effects, trigger allergic reactions, or interact with prescription and nonprescription medicines or other supplements you might be taking. A side effect or interaction with another medicine or supplement may make other health conditions worse.
  • The way dietary supplements are manufactured may not be standardized. Because of this, how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form of supplement that you buy in health food or grocery stores may not be the same as the form used in research.
  • Other than for vitamins and minerals, the long-term effects of most dietary supplements are not known.

Kava has been shown in more than a dozen placebo-controlled studies to be effective with good tolerability for treatment of generalized anxiety, with some evidence for stress, depression and insomnia. Kava is generally safe for short-term use but can in rare cases cause catastrophic damage to the liver. Thus, its use is very controversial, and the sources are split four to three on whether it should ever be recommended.

Mental Health Implications

Seven sources confirm the beneficial uses of kava as a mild intoxicant and analgesic, and for treatment of generalized anxiety, depression, stress, tension, agitation, agoraphobia, specific other phobias, generalized anxiety disorder, adjustment disorder, menopausal symptoms and insomnia. But Brown et al. caution that the benefits are “modest,” and all sources caution about the danger of liver damage. There is no proof that kava is effective for treatment of severe anxiety. No published studies have yet tested kava’s efficacy for panic disorders. Kava has not been found effective for adjunctive use, should not be used with MAOIs, and should only be used with tricyclics or SSRIs after careful coordination with the prescribing physician.

Drug Interactions

Kava has the potential to interact with several drugs and medications. It is vitally important to discuss kava use with any prescribing physician.
Alcohol, other sedatives, muscle relaxants, dopamine, haloperidol, acetaminophen, and benzodiazepines. Taking kava with alcohol, other sedatives, or muscle relaxants can result in additive effects up to and including coma. Kava may interact with several drugs, including drugs used for Parkinson’s disease and benzodiazepines used for anxiety. Alcohol or acetaminophen (Tylenol), which may injure the liver, should never be used with kava. Kava may interfere with the effects of dopamine and drugs that are similar to dopamine and may worsen the neurological side effects of drugs that block dopamine, such as haloperidol (Haldol).

Psychotropics and anesthesia. Kava may have chemical properties similar to monoamine oxidase inhibitors (MAOIs), and may be additive to the effects of MAOI antidepressants, such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate). Thus, kava should never be used with MAOIs. Adjunctive use with other psychotropic drugs, including tricyclic antidepressants and SSRIs, has not been tested, but should not be attempted without careful coordination with the prescribing physician. Kava may cause excessive drowsiness when taken with SSRI antidepressant drugs such as fluoxitine or sertraline. Kava may also cause anesthesia to last longer and use should be carefully coordinated with the prescribing physician or anesthesiologist.
Anti-cancer and birth control drugs. Kava may also interact with anti-cancer and birth control drugs.

Side Effects

Caution: Liver Toxicity: Reports from health authorities in Germany, Switzerland, France, Canada, and the United Kingdom have linked kava use to at least 30 cases of liver toxicity, including hepatitis, cirrhosis, and liver failure. Kava is banned in Germany, Canada and Switzerland. The U.S. FDA issued a consumer advisory in 2002, which is still in effect. The FDA cautions: Persons who have liver disease or liver problems, or persons who are taking drug products that can affect the liver, should consult a physician before using kava-containing supplements.
Of the consulted sources, Consumer Reports is the most directive: Based on the 2002 FDA warning, kava is one of 12 supplements that Consumer Reports advises that you should avoid. Brown et al. also do not recommend kava, and Fugh-Berman no longer recommends it, because of the catastrophic liver damage associated with its use in the cases noted by the FDA. Four sources still recommend careful use of kava. Lake and Spiegel, Mischoulon and Rosenbaum, the Natural Standard, and Weil counsel that kava should be avoided in individuals with a history of liver disease or alcohol use, and in those who are taking concurrent medications with potential liver toxicity. Mischoulon and Rosenbaum conclude: “Kava should be prescribed and used with great caution.” Use of kava is not recommended to exceed three months.

More research pinpointing risk factors could modify these recommendations, since liver toxicity appears to be extremely rare, and bad experience with other anxiolytics could prompt a trial of kava if the risk factors appear to be low, with proper medical supervision. Pregnancy, lactation or child use would appear not to impose a separate challenge.


Caution. The risk of liver damage is substantial and may be irreversible, even though it appears to be rare.

For detailed information on Kava and other treatments, download the full review.

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