Kava: Everything You Need to Know

Hands reaching for kava drinks.
Hands reaching for kava drinks.

Brandon Colbert Photography / Getty Images


The Food and Drug Administration (FDA) warns that using kava has been associated with liver injury. Consult with your healthcare provider before using kava-containing supplements, especially if you have or have had liver problems, you frequently drink alcoholic beverages, or you take any prescription or over-the-counter (OTC) medications.

Stop using kava if you develop symptoms that may indicate liver problems (e.g., yellowing of the skin or whites of the eyes, brown urine, light-colored stools, nausea, vomiting, unexplained tiredness, stomach pain, and loss of appetite).

Kava, also known as Piper methysticum, is a shrub from the Piperacea (pepper) family.

Traditionally, Pacific Islanders used kava extract as medicine and the beverage form of kava for religious and cultural ceremonies.

Kava is promoted to relieve stress and anxiety due to its main active components (parts or ingredients) called kavalactones.

The ways in which kavalactones work includes the following:

  • Reducing neurotransmitter (chemical messengers) release via blocking calcium ion channels
  • Enhancing the effect of gamma-aminobutyric acid (GABA), an inhibitory chemical messenger
  • Blocking voltage-gated sodium ion channels
  • Reversibly inhibiting the enzyme called monoamine oxidase B (which helps to balance certain levels of neurotransmitters in the body to help regulate mood)
  • Reducing the reuptake of dopamine and norepinephrine by the nerve cells

This article discusses the potential uses of kava. It also covers the side effects and risks of taking kava supplements.

Dietary supplements are not regulated the way drugs are in the United States, meaning the FDA does not approve them for safety and effectiveness before products are marketed. Choose a supplement tested by a trusted third party, such as U.S. Pharmacopeia (USP), ConsumerLab.com, or NSF, whenever possible. Note that even if supplements are third-party tested, they are not necessarily safe for all or effective in general. Therefore, talking to your healthcare provider about any supplements you plan to take and checking in about potential interactions with other supplements or medications is important.

Supplement Facts

  • Active Ingredient(s): Piper methysticum, kavalactones (e.g., methysticin, dihydromethysticin, dihydrokavain, demethoxyyangonin, and yangonin), flavokawains
  • Alternate Names(s): Kava-kava, kawa, kavain, rauschpfeffer, tonga, yaqona
  • Legal Status: OTC dietary supplement in the United States; water-soluble extracts of less than 250 milligrams (mg) of kavalactones per day allowed for medicinal use and is available OTC in Australia, other than in the Northern Territory of Australia; illegal in the United Kingdom (UK); can only be used under a prescriber’s orders in Germany (not for self-care).
  • Suggested Dose: Anxiety: 120–280 milligrams of kavalactones taken by mouth once a day for four to eight weeks. Sleep: 200 milligrams of kava extract taken by mouth every evening for four weeks 
  • Safety Considerations: Interactions with antidepressants, benzodiazepines, alcohol, certain OTC medications, and other prescription medications; impairment in motor skills (i.e., driving and operating heavy machinery); preexisting liver issues; pregnancy and breastfeeding. Common side effects: Tiredness, dizziness, nausea, stomach discomfort, daytime drowsiness, irregular heartbeat, impaired memory, and tremor. Serious side effects: Liver toxicity, increased liver function tests, dry scaling skin, and muscle-related side effects.

Uses of Kava

Kava has been studied for the following conditions:

  • Anxiety: An analysis of a group of clinical studies favored kava over placebo for treating mild-to-moderate generalized anxiety disorder (GAD). However, another study suggested conflicting results for GAD. Studies have compared kava to standard antianxiety medications like Buspar (buspirone) or benzodiazepines with mixed results. Further study is needed.
  • Anxiety-related sleep disturbances: Based on a study of 61 participants, kava was shown to help alleviate anxiety-related sleep disturbances, like insomnia. However, further studies with greater sample sizes are needed to confirm these findings. 
  • Cancer: Researchers have looked into kava for its anticancer uses. However, the outcomes were unclear, and more study is needed.


Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease. 

What Are the Side Effects of Kava?

Your provider may recommend you take kava for specific reasons. However, consuming an herb like kava may have potential side effects. These side effects may be common or severe.

Common Side Effects

Clinical trials have shown kava to be well-tolerated, with most reported mild side effects.

Some of the common side effects reported in clinical trials include the following:

No differences were found between kava and placebo (an inactive substance) on the following:

  • Withdrawal symptoms or addiction (in the context of both anxiety and sleep disturbances)
  • Blood pressure
  • Laboratory assessments
  • Sexual function (of note, another study showed that kava was found to increase sexual drive in people designated female at birth but did not have negative sexual effects in people assigned male at birth)

Severe Side Effects

Heavy, prolonged use of kava or the use of poor-quality kava products has been associated with the following serious side effects:

If you're having a severe allergic reaction or if any of your symptoms feel life-threatening, call 911 and get medical help right away.


Due to concerns over reported liver toxicity, kava was withdrawn from European, and United Kingdom markets in 2002.

Exercise caution when taking kava if you are:

  • Driving and operating heavy machinery (when using high doses of kava)
  • Drinking alcohol
  • Taking certain medications, such as benzodiazepines or Tylenol (acetaminophen)
  • Having preexisting liver issues (routine liver function tests are advised for regular users)
  • Having cancer, which can compromise liver function as a side effect of chemotherapy
  • Having upcoming surgery (kava should be stopped at least five days before surgery with general anesthesia)
  • Pregnant or breastfeeding

Severe allergic reaction: Avoid using kava if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Dosage: How Much Kava Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.

While there's no standard dosage for kava, studies have used the following dosages:

  • Anxiety: 120 to 280 milligrams per day of kavalactone (tablet form) by mouth for four to eight weeks.
  • Sleep disturbances: 200 milligrams of kava extract (capsule form) by mouth once daily in the evening for four weeks.

What Happens If I Take Too Much Kava?

Higher kava doses may impair motor skills and reaction time, posing a risk when driving or operating heavy machinery.

Most jurisdictions recommend not exceeding 240 to 250 milligrams of kavalactones per day.

Scientific evidence does not support the long-term use of kava products.

The World Health Organization (WHO) has established that liver toxicity due to kavalactones was more likely caused by overdosing and excessive alcohol intake, pre-existing liver disease, and kava-drug interactions.

If you feel you've ingested too much kava, please ask for immediate guidance from a healthcare provider.


It is advisable to avoid taking kava with the following:

  • Antidepressants
  • Benzodiazepines
  • Alcohol (using kava with alcohol may increase the risk of liver damage)
  • OTC medications (e.g., taking Tylenol with kava may increase the risk of liver damage)
  • Certain herbal remedies
  • Other medications that are metabolized by CYP3A4 or 2D6 pathways (these are the drug-metabolizing enzyme systems)

It is essential to carefully read a supplement's ingredients list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How to Store Kava

Store kava supplements in a cool, dry place away from children and pets. Keep kava supplements away from direct sunlight. Discard as indicated in the packaging.

Similar Supplements

Other supplements with similar properties as kava include the following:

Similar to kava, the herbs listed above have been shown to improve anxiety.

Among the herbs listed above, saffron, lavender, passionflower, chamomile, and valerian have also been shown to improve sleep, similar to kava.

Some products marketed as a calming and sleep remedy combine kava with passionflower, chamomile, valerian, and gotu kola.

Sources of Kava & What to Look For

What portion of the plants is used and how kava is prepared can affect liver toxicity.

For example, preparations made from the kava plant's root are generally safer than stems or leaves, which may be more toxic.

Kava products prepared via water-based extraction methods are advised instead of those prepared with ethanol and acetone.

Water extracts are preferred because they are rich in liver-protective compounds called glutathione.

Note also that kava's medicinal use in tablet form has a significantly lower dose than the powdered extract form used for recreational consumption.


Kava has been traditionally consumed as a ceremonial drink by people from the Pacific Islands, and its extracts have been promoted to improve anxiety and sleep.

However, liver toxicity, impaired motor skills, and dry scaling skin have been reported due to heavy or prolonged use of kava products, especially those of poor quality.

When buying kava, look for water-based kava extract from the plant's root.

It is essential to consult with your healthcare provider before starting kava as it can interact with prescription and nonprescription medications and alcohol.

Frequently Asked Questions

  • How does kava affect the body?

    Kava’s anxiety-reducing effect is due to the kavalactones (the active ingredients in kava) that work to enhance specific gamma-aminobutyric acid (GABA) receptors. This results in a reduction of excitatory neurotransmitter release and a limitation in the nerve cells' reuptake of dopamine and norepinephrine.

  • Who should not take kava?

    You should not take kava if you have liver problems, take certain prescription medications (e.g., benzodiazepines) or over-the-counter medications (e.g., Tylenol acetaminophen), drink excessive alcohol, or have certain medical conditions. Speak with your healthcare provider to determine if kava is appropriate for you.

  • How can I ensure I’m getting safe kava products?

    To ensure you get safe kava products, look for water-soluble extracts of the kava root and avoid products sourced from kava stems or leaves and products prepared by ethanol or acetone extraction methods. Additionally, avoid using kava products with alcohol and other psychotropic medications. High doses of kava should be avoided if driving or operating heavy machinery.

21 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Trang Tran, PharmD
Trang Tran, PharmD, is a pharmacist who is passionate about integrative health.