Kava

Pacific cultural context

The World Health Organization (WHO) report on kava describes it as the name used in South Pacific island countries for a traditional drink made from the root or rhizome of Piper methysticum, and says the drink has been used for centuries. The US National Center for Complementary and Integrative Health (NCCIH) says Pacific Islanders have used the plant for thousands of years in ceremonies and as medicine. Neither source gives a dated primary record for the first use, so the length of that history is stated here as the sources state it.

A 2025 narrative systematic review of 197 records, which included ethnographic and community-based research, found that all studies of social and cultural reasons for use came from Oceania and the South Pacific. Kava was described as central to funerals, weddings and other special occasions, to cultural identity and connection to place, and in some settings to church life and the preservation of language and song. The review also noted that practices vary by region, and this page does not describe ceremonial protocols, which are held and taught within the communities concerned.

Spread into supplements and kava bars

The WHO report says European travellers noted that Pacific Islanders relaxed after drinking kava, and that later laboratory work identified the kavalactones as the main pharmacologically active group. European pharmaceutical companies then made capsules and tablets from concentrated extracts, and the report says stem peelings became a cheap raw material for such products in Europe in the late 1990s. The 2025 review adds that kava was first imported into Australia in the early 1980s and that between 500 and 4000 tonnes were exported from Vanuatu, Fiji and Tonga each year from 2015 to 2019.

NCCIH says that in the United States kava is sold as a dietary supplement and served as a beverage in kava bars, while some other countries treat it as a drug or herbal medicine. An analysis of 423 social media posts from 2006 to 2021 reported that use in the United States has risen slowly since the 1990s and is not assessed in major national surveys. That analysis rests on self-selected posts and does not measure how many people use kava.

Names for the plant and the drink

The word kava is used for the plant, for the traditional drink and, in commercial settings, for extracts and capsules made from the plant. NCCIH lists kava kava, awa and ava pepper as other names. The 2025 review searched under many local and regional terms to capture different cultures and countries, among them yaqona, sakau, awa, ava, wati, waka, lewena, kawa and the slang term grog. The sources opened for this page do not assign each term to a particular island group, so those links are not stated here.

Kavalactones and extract types

Kavalactones, also called kava pyrones, are the group of compounds the WHO report identifies as the main pharmacologically active components; it names kawain, yangonin, methysticin, dihydromethysticin, demethoxyyangonin and dihydrokawain as the most important. The report separates three product types: water extracts, including the traditional microsuspension in water and teas made from powdered root; organic extracts made with ethanol or acetone; and synthetic products. It states that these are not chemically equivalent, and that organic solvents dissolve about thirty compounds that water does not.

Researchers also use the phrase noble cultivar for varieties considered suitable for drinking. One hepatology review argued that using unsuitable cultivars or plant parts, instead of the root of a noble cultivar, may have contributed to liver injury, and the WHO report called for agreement on which cultivars should be used. How a cultivar should be defined is not settled in the sources opened here.

Forms of kava in general terms

In Pacific communities the traditional product is a drink made from the root or rhizome mixed with water, taken in social and ceremonial gatherings, according to the WHO report. A 2022 study of a Tongan community kava-drinking session described sessions that lasted about six hours, with attendees drinking an average of 3.6 liters each. The 2025 review reports that serving practices and frequency vary, from everyday use in some areas of Fiji to use only at major occasions such as funerals and weddings in others.

Outside the Pacific, kava appears as capsules, tablets and liquid extracts sold as supplements, and as beverages in kava bars. The WHO report notes that the extracts used in Europe and North America were mostly made with ethanol or acetone, and it separates those from the traditional water preparations. This page does not give amounts or methods of preparation.

Plant parts and product quality

The WHO report states that raw materials for kava products have come from a variety of sources without adequate quality control, cultivar selection or plant-part standardization. It recommends that only the root or rhizome of Piper methysticum be used for medicinal kava and not aerial parts, and that a pharmacopoeial standard be created. NCCIH lists undesirable cultivars or plant parts, adulteration and contamination among factors that may contribute to liver injury, so consumers cannot assume that two kava products are equivalent.

Cultural and social purposes

In the 2025 review, 15 of 25 records on social and cultural use described kava as a recreational and social activity that supports bonding and alliances, and four described it as a means of asking forgiveness or resolving conflict. Three records described it as part of a person's identity, and seven described social order or rank in who drinks. Some papers stressed that its calming and passive effects differ from alcohol, while two records described it as an alternative to alcohol.

Uses promoted for supplements and drinks

NCCIH says kava products are promoted for anxiety and other conditions, and that the evidence is insufficient for any condition other than anxiety. In the 2025 review, 34 of 37 records on benefits described improved mood, relaxation or reduced anxiety, stress or sleep problems. A study of United States social media posts found that people described using kava both for self-treatment of psychiatric or physical conditions and for recreation, and that the two were not mutually exclusive.

Cochrane review of kava extract for anxiety

A Cochrane review by Pittler and Ernst (2003 version, searches to August 2002) included 11 randomized, double-blind, placebo-controlled trials with 645 participants. A meta-analysis of six trials using the Hamilton Anxiety scale total score (345 participants) found a mean difference of 5.0 points favoring kava extract over placebo (95% confidence interval 1.1 to 8.8). Adverse events in the reviewed trials were described as mild, transient and infrequent. The authors called for rigorous studies of long-term effects, and the trials lasted 1 to 24 weeks.

Trials with water-based extracts in generalized anxiety disorder

A 2013 six-week trial enrolled 75 adults with generalized anxiety disorder and analyzed 58 who completed a placebo run-in, using a water-based (aqueous) kava extract. Anxiety fell more with kava than placebo (P = 0.046, effect size d = 0.62), and 26% of the kava group were classed as remitted compared with 6% on placebo. More headaches occurred with kava, and liver function tests did not differ between groups.

A larger, longer trial published in 2019 enrolled 171 adults with generalized anxiety disorder for 16 weeks using an aqueous extract of dried root. The difference in anxiety reduction was not significant and numerically favored placebo (1.37 points, P = 0.25), and 17.4% of the kava group and 23.8% of the placebo group were classed as remitted. Memory problems and tremor were reported more often with kava, and liver function test abnormalities were more frequent with kava, although no participant met criteria for herb-induced liver injury. The authors concluded that this extract was not effective for diagnosed generalized anxiety disorder, and NCCIH states that kava does not appear to be helpful for generalized anxiety disorder symptoms.

Water-based and organic-solvent extracts

The trials in the Cochrane review used a range of kava extracts, and the WHO report lists most clinical trial products as ethanolic or acetonic extracts. The 2013 and 2019 trials both used aqueous extracts and gave different results, so the choice of solvent does not on its own explain the pattern of findings. The authors of the 2019 trial suggested that research may support kava more for short-term, situational anxiety than for diagnosed generalized anxiety disorder, which is a hypothesis and not a finding of that trial.

Limits of the evidence

The 2025 review found that eight randomized trials reported significant anxiety reductions with kava compared with placebo and three reported no significant difference. It also found that almost all non-randomized studies had a high risk of bias, that heterogeneity prevented a meta-analysis, and that the effects of regular use over months or years remain unclear. The sources opened for this page did not include the later Cochrane updates or the 2010 review mentioned in some summaries, so those are not described.

Liver injury reports

The WHO risk assessment reviewed 93 case reports of liver problems with kava products, noting that most were incomplete. Seven patients had died and 14 had received liver transplants. Eight cases were rated probable, 53 possible, and five showed a positive rechallenge. The report concluded that kava lactones in any product may rarely cause liver reactions, that acetonic and ethanolic extracts appeared hepatotoxic on rare occasions, and that incidence is unknown. Clinical trials had not revealed liver toxicity.

NCCIH says various kava products have been linked to rare cases of liver injury, some serious or fatal, involving both alcohol or acetone extracts and water-prepared beverages. Such reports led health authorities in several countries to restrict kava-containing products in the early 2000s, as summarized in the WHO report and the 2025 review; individual decisions are not described here.

Disputed mechanisms and risk factors

Reviews disagree on how much the extraction solvent matters. A causality assessment of 14 patients reported a similar clinical picture with aqueous, ethanolic and acetonic extracts, and its author attributed toxicity to the plant, cultivar or plant-part quality. The WHO report found a higher rate with organic extracts than with synthetic products and suggested non-kavalactone constituents. Proposed contributors include overdose, prolonged use, combined medicines, mold toxins and poor-quality raw material; the mold hypothesis needs further study, and NCCIH adds genetic differences and alcohol use.

Interactions, sedation and driving

NCCIH advises against combining kava with other sedating substances such as benzodiazepines or alcohol. The WHO report states that kava products have a strong propensity for interactions and lists heavy alcohol intake, liver disease and use of other anxiolytics, antipsychotics or antithrombotics as concerns.

A study of 20 kava drinkers and 19 controls during a traditionally styled six-hour session found impaired temporal order judgment at the final test, with no significant impairment in five other measures; the authors judged that driver safety may be affected. The 2025 review found conflicting reports on driving, with three records suggesting impairment and four finding none.

Skin effects and heavy use

NCCIH says long-term high-dose use may cause kava dermopathy, with dry, scaly skin and temporary yellowing of skin, hair and nails. A 2026 case report described an itchy red eruption in a 41-year-old woman after six weeks of use for anxiety and insomnia, with mild liver function test changes. The 2025 review noted it is unclear how far such harms are attributable to kava.

Who should ask a clinician

Kava does not replace assessment of anxiety, and persistent symptoms are a reason to see a clinician. NCCIH says kava may carry special risks in pregnancy and breastfeeding. People with liver disease, heavy alcohol use, or prescriptions for sedatives, antipsychotics or blood thinners should ask a clinician or pharmacist first. Yellowing of the skin or eyes, dark urine or severe abdominal pain need prompt medical attention.