Kava root preparations reduce stress-related anxiety and the effects of anxiety disorders. Studies show that these antianxiety effects are significant, superior to placebo, and similar to effects of benzodiazepines used in the treatment of anxiety without causing similar adverse side effects. Kava also reduces anxiety associated with or precipated by menopause, and it is a topical oral anesthetic. Kava promotes sleep in larger doses and a state of calm in smaller doses. The effects of kava are relaxing, not stupefying; it disposes users to sociability, not hostility.

The kava plant comes from Oceania, the geographical area of Polynesia, Micronesia, and Melanesia in the Pacific Ocean. Kava consumption among native peoples was first discovered during Captain James Cook's Endeavour voyage (1768 to 1771). The Swedish botanists who accompanied Captain Cook recorded kava as an indigenous intoxicant. Tribes used kava as a ceremonial as well as social drink, with different purposes and rituals surrounding its use, including which members were allowed to drink it. Despite the efforts of the 19th century Christian missionaries to quash kava use, today kava is available at kava bars on some islands and provides a good living for exporters, who cultivate kava commercially. It is often presented as a gift of honor and goodwill to dignitaries and foreigners at welcoming ceremonies. President and Mrs. Lyndon B. Johnson, Hillary Rodham Clinton, and Pope John Paul II have participated in kava ceremonies.

Kava was available in some parts of Germany by the late 19th century, but it was rare. Despite its long-standing use in Hawaii, Kava has caught on only recently in the mainland U.S. as a popular herbal medicine. In the past three years, kava has been the subject of intense marketing and may soon exceed South Pacific supply. Its safety and regulation are also current points of controversy. While side effects effects are mild (the most frequently reported are GI discomfort, headache, dizziness, or skin rash occuring in a small percentage of study participants), excess amounts of kava impair driving ability. Yellowing of the skin, hair, and nails, and drying and cracking of the skin is seen in some chronic users, as is disturbance to vision or oculomotor equilibrium. And because so many recovered substance abusers are taking kava daily, its addictive potential is still under question, despite the lack of demonstrable evidence from a 1994 addiction potential study.

Kava is an erect, branching shrub with prominent, succulent leaves. It grows up to six meters in damp tropical climates. The heart-shaped green leaves are smooth and pointed; erect yellow-green inflorescence develops at axils. The rhizome is harvested when it is 5 to 8 cm thick, after three to five years' growth, when the plant is 2 to 2.5 m tall. Numerous long, bundled, tuberous hairs grow from the rhizome.

• Roots[rhizome]

Dried herb contains 3.5% kavapyrones, including 1% to 2% kawain, 0.6% to 1% dihydrokawain, 1.2% to 2% methysticin, and 0.5% to 0.8% dihydromethysticin.

In some cultures, the method of preparation involved chewing the root and spitting the juice into a bowl; saliva served as a macerate. Today, manufacturers use alcohol-water or acetate macerations or percolations to extract kava's active constituents from ground rhizome. Kava is available as aqueous-alcohol extracts and encapsulations, standardized to 70% kavalactone content, and as tinctures, tablets, and dried root.

Traditional actions: Antispasmodic, nervine, relaxant, anti-anxiety, anesthetic, diuretic. Historically used for gonorrhea, chronic cystitis or other urinary tract symptoms, menstrual disorder and migraines, but it is not used for these now. Currently used as a relaxant of skeletal muscles for pain and stiffness, anxiety, insomnia, menopausal anxiety, uncontrolled epilepsy, pain, and jet lag.

Conditions: anxiety, insomnia

Clinical applications: stress-related anxiety, anxiety disorder, phobias, restlessness, insomnia

By 1998, six human double-blind, controlled trials on kava's therapeutic effects had been conducted. These trials demonstrate consistent, significant antianxiety effects of kava, although the methodologies of some are questionable. One recent study (1997) found a standardized, 70% kavalactone kava extract superior to placebo in treating nonpsychotic patients. Of 101 outpatients who met DSM-III-R criteria and participated in the study, 52 received kava, and symptoms in the majority of this group improved throughout the 25-week study, some noting improvements by week eight. Results from the Hamilton Anxiety Scale, somatic and psychic anxiety, Clinical Global Impression, Self-Report Symptoms Inventory, and Adjective Mood Scale not only show kava's superiority to placebo in the treatment of nonpsychotic anxiety, but also support kava's use in lieu of tricyclic antidepressants and benzodiazepine drugs.

Individual effects of kava constituents have also been investigated. The kavapyrones (kawain, dihydrokawain, methysticin, dihydromethysticin)are anticonvulsant, central muscle relaxants (similar to mephenesin) and locally anesthetic. They are also superior to strychnine antagonists in preventing strychnine poisoning in animal tests. In rabbits, these constituents diminish excitability of the limbic system similar to benzodiazepines, and are also neuroprotective in mice and rats. In addition, nine studies have analyzed the effects of isolated dihydrokawain (DL-kawain) in anxiety disorder, with results similar to those of whole extract preparations.

To relieve anxiety and insomnia, and reduce stress, standard dose is 2.0 to 4.0 g as decoction up to three times daily, or standardized formulas (containing 70% kavalactones) for a daily intake of 60 to 600 mg kavalactones. Treatment length varies: it may take four weeks to reach peak therapeutic effect. In Germany and Australia, patients are advised not to continue dosing longer than three months.

Typical side effects are mild, and include allergy (skin rash), headache, gastrointestinal distress, and dizziness. The American Herbal Products Association recommends that kava not be used during pregnancy or while breast-feeding (class 2b and 2d); also, do not drive when using excessive dosages (class 2d).

Extreme doses of 13 liters per day—300 to 400 g dried rhizome per week—resulted in yellowing of the skin, ataxia, rash, hair loss, and changes in vision, appetite, and respiration. This dose exceeds recommended doses by 100 times.

Do not use during pregnancy or while breast-feeding. Do not exceed recommended dose or length of treatment.

The German Commission E monograph for this herb indicates that kava may potentiate the effects of substances, such as barbiturates and other psychopharmacological agents (Blumenthal 1998). There has been a case report of an interaction between alprazolam and kava that resulted in coma in a 54-year-old man (Almeida and Grimsley 1996). Although the patient's medications also included cimetidine and terazosin hydrochloride, the kava-alprazolam interaction was presumed to be the cause of his condition. Information regarding the doses of kava or alprazolam was not included in the report but the patient denied overdosing on either substance.

There is a case report of a possible interaction between kava and levodopa (Schelosky et al. 1995). Kava reportedly decreased the effectiveness of levodopa, presumably because of dopamine antagonism. The patient was a 76-year-old female who had been maintained on levodopa (500 mg/day) for eight years for the treatment of Parkinson's disease. When kava extract (150 mg bid) was added to her medication regimen, she noted an increase in the duration and number of dyskinetic episodes within 10 days. Discontinuation of the kava resulted in a return to baseline patterns for this patient within two days.

Patients taking phenothiazines may be at increased risk of developing extrapyramidal side effects if these medications are combined with kava (Schelosky et al. 1995).

Kava is a dietary supplement in the U.S. and approved for use by the German Commission E in the treatment of anxiety and restlessness. Not approved in Canada for nonmedicinal inclusion in oral preparations.

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