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.
Kava works as a treatment for generalized anxiety, depression, stress, tension, agitation, agoraphobia, specific other phobias, generalized anxiety disorder, adjustment disorder, menopausal symptoms and insomnia. There is no proof that kava is effective for treatment of severe anxiety. No published studies have yet to test kava's efficacy for panic disorders.
Kava has the potential to interact with several drugs and medications. It is vitally important to discuss kava use with any prescribing physician.
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).
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.
Kava may also interact with anti-cancer and birth control drugs.
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. The risk of liver damage is substantial and may be irreversible, even though it appears to be rare.