Common Names

  • Kava-kava
  • Kawa
  • Kavain
  • Rauschpfeffer
  • Tonga
  • Yaqona

For Patients & Caregivers

Kava may be effective in reducing anxiety, but liver toxicity is a major concern.

The active compounds in kava are called kavalactones. In studies in animals and humans, these compounds provide pain relief and act as muscle relaxants and anticonvulsants. Kavalactones might act the same way as the antidepressant drugs, monoamine oxidase inhibitors (MAOIs). Scientists are not sure whether they change the levels of the hormones dopamine and serotonin in the brain.

Kava is known to cause liver damage.

  • To treat anxiety and stress
    Several clinical trials support this use. However, the clear risk of liver damage from kava use outweighs any benefits.
  • To treat insomnia
    No scientific evidence supports this use.
  • Kava may cause liver damage. The British, French, German, and Swiss governments have requested that kava be removed from the market. The Canadian government has warned consumers not to use kava-containing products.
  • Overdose or long-term use can cause low blood platelets and white blood cells, dry flaking skin known as kava dermopathy, respiratory problems, and hearing impairment. Inform your doctor immediately if you have any of these symptoms.
  • Kava may impair your ability to drive or operate heavy machinery.
  • You have liver or kidney problems: Kava may worsen them.
  • You are taking benzodiazepines such as Ativan®, Xanax®, Serax®, Valium®, or Tranxene®: Kava may increase sedation.
  • You drink alcoholic beverages: Kava may increase sedation. Avoid using kava and alcohol at the same time.
  • You are taking barbiturates: In theory, kava may increase sedation and muscle-relaxant effects.
  • You take sedatives: In theory, kava may increase sedation.
  • If you are taking cytochrome P450 substrate drugs: Kava may increase the risk of side effects of these drugs.
  • You take acetaminophen: Kava increased the liver toxicity caused by acetaminophen in laboratory studies.
  • Headache
  • Impaired reflexes or judgment
  • Visual disturbances
  • Sedation
  • Restlessness
  • Tremor
  • Hangover effect
  • Liver damage (rare): Immediately inform your doctor if you have yellowish discoloration of the skin, eyes, fingernails or toenails, nausea, or vomiting.
  • Overdose or long-term use can cause low blood platelets and white blood cells, dry flaking skin known as kava dermopathy, respiratory problems, and hearing impairment. Inform your doctor immediately if you have any of these symptoms.
  • Although kava may provide short-term relief for anxiety, the risk of liver damage outweighs any benefits.
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For Healthcare Professionals

Piper methysticum

Derived from the rhizome of the plant, kava is from the Pacific Rim and Hawaiian Islands. It is used as a social beverage in those areas and to relieve anxiety, stress, and insomnia. Kavalactones in kava are thought to be the active constituent that produces skeletal muscle relaxation, non-narcotic anesthesia, and local anesthetic effects.

An Internet-based study showed that kava is not superior to placebo in reducing anxiety (3), and a randomized clinical trial reported similar findings (36). However, data from several studies support the use of kava for relieving anxiety (1) (25) (26). It has also been suggested as an alternative to benzodiazepines, which are used to treat anxiety. A systematic review showed that kava does not have negative effects on cognition  (37).

Although available data suggest kava’s benefits for anxiety, the Canadian, French, and British governments withdrew kava and kava-containing products due to concerns of hepatotoxicity (4) (11) (23).

The Food and Drug Administration (FDA) has advised consumers about the potential risks of liver injury associated with kava consumption. However, following a World Health Organization (WHO) recommendation to study aqueous extracts of kava, initial research results support the benefits of kava (27) (28). Case analyses of 14 patients with hepatic injury resulting from kava use revealed low-quality products, overdose, prolonged use and co-medication as causative factors (29). Additional studies are needed to confirm these findings.

Kava consumption has been associated with low cancer incidence (30), but one of its constituents was shown to stimulate growth of melanoma cells (31).

  • Insomnia
  • Restlessness
  • Stress

Kavapyrones are centrally-acting skeletal muscle relaxants, anticonvulsants, and peripherally-acting local anesthetics. There are conflicting data on the effects of kavapyrones on CNS levels of dopamine and serotonin (14). Possible hepatotoxicity mechanisms are thought to be cytochrome P450 inhibition, reduction in liver glutathione content, or inhibition of cyclooxygenase (COX) activity (4) (15).

In vitro and in vivo studies suggest that kavapyrone- and pipermethystine-containing extracts induce mitochondrial dysfunction, oxidative stress, and apoptosis of Hep2G cells (16) (17).

Kava enhances acetaminophen-induced cytotoxicity by increasing glutathione (GSH) depletion, resulting in oxidative stress and mitochondrial dysfunction, ultimately resulting in cell death (35).

  • Kava may cause hepatotoxicity, and elevated gamma-glutamyl transpeptidase (GGT) levels were detected in regular kava drinkers (20).
  • The British, French, and Swiss governments have requested that kava be removed from the market (11).
  • The Canadian government has warned consumers not to use kava-containing products (21).
  • Discontinue kava use before surgery as it may interact with anesthetics. Kava may also impair ability to drive or operate heavy machinery (6).
  • Hepatotoxicity (4) (23), urticaria (32), and reversible dermopathy (22) following use of kava.
  • Overdose of kava resulted in altered mental status and ataxia (33).

Benzodiazepines: Kava may enhance sedation when administered concurrently. Kava indirectly increases the affinity of GABA receptor binding sites in vitro (24).
Barbiturates: Theoretically, kava may have an additive effect on sedation and muscle-relaxant activity; however, this has only been demonstrated in animals.
Sedatives: Theoretically, kava may have an additive effect with any centrally-acting medication that can potentially cause sedation (5).
Cytochrome P450 substrates: Kava inhibits CYP2E1 (7), 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4 (8) (9) (34), and can affect the intracellular concentration of drugs metabolized by these enzymes. Another study shows Kava extracts can induce CYP2E1 and CYP1A2 in an animal model (16).
Acetaminophen: Kava enhances the hepatic cell-cytotoxicity induced by acetaminophen in vitro (35).

  1. Pittler MH, Ernst E. Efficacy of kava extract for treating anxiety: systematic review and meta-analysis. J Clin Psychopharmacol. Feb 2000;20(1):84-89.

  2. Jacobs BP, Bent S, Tice JA, Blackwell T, Cummings SR. An internet-based randomized, placebo-controlled trial of kava and valerian for anxiety and insomnia. Medicine (Baltimore). Jul 2005;84(4):197-207.

  3. Clouatre DL.Kava kava: examining new reports of toxicity. Toxicol Lett. Apr 15 2004;150(1):85-96.

  4. Brinker F. Herb Contraindications and Drug Interactions. 3rd ed. Sandy (OR): Eclectic Medical Publishers; 2001.

  5. Ang-Lee MK, Moss J, Yuan CS. Herbal medicines and perioperative care. JAMA. Jul 11 2001;286(2):208-216.

  6. Gurley BJ, Gardner SF, Hubbard MA, et al. In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4/5 phenotypes. Clin Pharmacol Ther. May 2005;77(5):415-426.

  7. Russmann S, Lauterburg BH, Barguil Y, et al. Traditional aqueous kava extracts inhibit cytochrome P450 1A2 in humans: Protective effect against environmental carcinogens? Clin Pharmacol Ther. May 2005;77(5):453-454.

  8. Russmann S, Lauterburg BH, Helbling A. Kava hepatotoxicity. Ann Intern Med. Jul 3 2001;135(1):68-69.

  9. Pittler MH, Ernst E. Kava extract for treating anxiety. Cochrane Database Syst Rev. 2003(1):CD003383.

  10. Burros M. EATING WELL; New questions about kava’s safety. The New York Times. January 16, 2002, 2002;F.

  11. Jhoo JW, Ang CY, Heinze TM, et al. Identification of C-glycoside flavonoids as potential mutagenic compounds in kava. J Food Sci. Mar 2007;72(2):C120-125.

  12. Foster S, Tyler VE. Tyler’s Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. New York: Haworth Herbal Press; 1999.

  13. Robbers JE, Speedie MK, Tyler VE. Pharmacognosy and pharmacobiotechnology. Baltimore: Williams & Wilkins; 1996.

  14. Lim ST, Dragull K, Tang CS, Bittenbender HC, Efird JT, Nerurkar PV. Effects of kava alkaloid, pipermethystine, and kavalactones on oxidative stress and cytochrome P450 in F-344 rats. Toxicol Sci. May 2007;97(1):214-221.

  15. Lude S, Torok M, Dieterle S, Jaggi R, Buter KB, Krahenbuhl S. Hepatocellular toxicity of kava leaf and root extracts. Phytomedicine. Jan 2008;15(1-2):120-131.

  16. Keledjian J, Duffield PH, Jamieson DD, Lidgard RO, Duffield AM. Uptake into mouse brain of four compounds present in the psychoactive beverage kava. J Pharm Sci. Dec 1988;77(12):1003-1006.

  17. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician’s Guide to Herbal Medicine. 4th ed. New York: Springer; 2001.

  18. Brown AC, Onopa J, Holck P, et al. Traditional kava beverage consumption and liver function tests in a predominantly Tongan population in Hawaii. Clin Toxicol (Phila). Jun-Aug 2007;45(5):549-556.

  19. Canadian Adverse Reaction Newsletter. http://www.hc-sc.gc.ca/dhp-mps/medeff/bulletin/carn-bcei_v12n4-eng.php#a3. 2002; (12):4. Accessed February 13, 2013.

  20. Norton SA, Ruze P. Kava dermopathy. J Am Acad Dermatol. Jul 1994;31(1):89-97.

  21. Escher M, Desmeules J, Giostra E, Mentha G. Hepatitis associated with Kava, a herbal remedy for anxiety. BMJ. Jan 20 2001;322(7279):139.

  22. Almeida JC, Grimsley EW. Coma from the health food store: interaction between kava and alprazolam. Ann Intern Med. Dec 1 1996;125(11):940-941.

  23. Sarris J, Kavanagh DJ, Byrne G, Bone KM, Adams J, Deed G. The Kava Anxiety Depression Spectrum Study (KADSS): a randomized, placebo-controlled crossover trial using an aqueous extract of Piper methysticum. Psychopharmacology (Berl). 2009 Aug;205(3):399-407.

  24. Singh YN, Devkota AK. Aqueous kava extracts do not affect liver function tests in rats. Planta Med. 2003 Jun;69(6):496-9.

  25. Steiner GG. The correlation between cancer incidence and kava consumption. Hawaii Med J. 2000 Nov;59(11):420-2.

  26. Matsuda H, Hirata N, Kawaguchi Y, et al. Melanogenesis stimulation in murine B16 melanoma cells by Kava (Piper methysticum) rhizome extract and kavalactones. Biol Pharm Bull. 2006 Apr;29(4):834-7.

  27. Grace R. Kava-induced urticaria. J Am Acad Dermatol. 2005 Nov;53(5):906.

  28. Perez J, Holmes JF. Altered mental status and ataxia secondary to acute Kava ingestion. J Emerg Med. 2005 Jan;28(1):49-51.

  29. LaPorte E, Sarris J, Stough C, Scholey A. Neurocognitive effects of kava (Piper methysticum): a systematic review. Hum Psychopharmacol. 2011 Mar;26(2):102-11.

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