Awaiting clinical review. This entry is sourced but has not yet been signed off by a pharmacist or clinician.

Piper methysticum (root)

Kava

Kava may ease anxiety in the short term, but the evidence is mixed: a Cochrane review of seven older trials favoured it over placebo, while a 16-week trial in people with diagnosed generalised anxiety disorder found no benefit. It has been linked to rare but sometimes fatal liver injury, so the main caution is liver safety, and it should not be combined with alcohol or sedatives. What the evidence cannot tell you is which products, doses or people carry the liver risk.

Written by

Healthy and Herbal editorial team

Updated

29 September 2026

At a glance

Last reviewed 29 September 2026

Evidence

Limited

Best for

Short-term anxiety

Typical form & use

Aqueous root extract, 120–240 mg/day

Onset

2 weeks

Safety

Rare serious liver injury; never with alcohol. 2 known interactions, most serious with alcohol.

Check with your medications →

What it's used for

Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.

Use	Evidence	What the research shows
Short-term anxiety	Limited	The 2002 Cochrane review pooled three trials using the Hamilton Anxiety scale and found kava ahead of placebo (weighted mean difference 9.7 points, 95% CI 3.5 to 15.8), but its searches ran only to 1998. A 2018 review found kava beat placebo in 3 of 7 trials, with a pooled responder risk ratio of 1.50 (95% CI 1.12 to 2.01) across 5 trials (n = 330). NCCIH says kava supplements may help anxiety, and may take several weeks to work.^1,2,6
Diagnosed generalised anxiety disorder	Limited	Results conflict. A 6-week trial of 58 analysed adults found a moderate benefit (Cohen d = 0.62). A larger 16-week trial of 171 adults with an aqueous extract found no significant difference, with the point estimate slightly favouring placebo (1.37 points) and remission in 17.4% on kava versus 23.8% on placebo. Three earlier small trials (n = 64 pooled) also found no difference. NCCIH says kava does not appear helpful for generalised anxiety disorder.^3,4,5,6
Other conditions	Traditional	NCCIH says there is not enough evidence to show whether kava helps any condition other than anxiety. Kava has been used ceremonially and medicinally in the Pacific for thousands of years.⁶

How much

Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.

Studied dose

120–240 mg kavalactones a day^3,4

In the 2013 and 2020 Australian trials, an aqueous root extract was taken twice a day, 120 mg of kavalactones a day in one, titrated to 240 mg in non-responders. Earlier trials used other extracts and doses that we did not extract.

Time to effect

Several weeks⁶

NCCIH says kava may need to be taken for several weeks to work. The Cochrane and 2018 reviews do not give a single dose or duration that we can quote.

Duration

Short courses only^2,6

The 2018 review's authors describe kava as a short-term treatment and say liver toxicity is especially possible beyond 8 weeks, although they did not see it in the trials reviewed. NCCIH says large amounts or prolonged use may increase liver risk.

Timing · The 2013 and 2020 trials gave the extract twice a day. No source we read gave advice on time of day.With food? · No source we read gave advice about food.How long to trial · NCCIH says effects may take several weeks. The trials ran 6 and 16 weeks, but no source we read set a stopping rule, so ask a clinician before extending a course.

How people take it

Tablet (aqueous root extract)120–240 mg kavalactones a dayThe form used in the two Australian trials; water-based extraction of the root.

Kava drink (water-prepared)No standard doseNCCIH notes kava drinks are sold at kava bars in the US, and that some liver injury cases involved water-prepared beverages.

Alcohol or acetone extract supplementVaries by productNCCIH says the first reported liver injury cases involved products extracted with alcohol or acetone.

Safety

Who should avoid

Liver problems — kava has been linked to serious liver injury (NCCIH)
Pregnancy and breastfeeding — NCCIH cites harmful pyrone constituents
With alcohol — NCCIH says not to combine
With benzodiazepines or other sedatives — NCCIH says not to combine
Long courses or high doses — may raise liver risk

Known interactions

AvoidAlcohol — NCCIH says kava should not be used together with alcohol, and lists alcohol among the possible explanations for liver toxicity cases.

CautionSedatives & sleep medication — NCCIH says kava should not be used together with other substances that have sedative effects, such as benzodiazepines.

Questions people ask

Does kava work for anxiety?

Possibly, in the short term. The Cochrane review and a 2018 review favoured kava over placebo, but the largest and longest trial in generalised anxiety disorder (171 people, 16 weeks) found no benefit. NCCIH says it may help anxiety but does not appear helpful for generalised anxiety disorder.

Is kava dangerous for the liver?

Rarely, but seriously. NCCIH reports cases of liver injury linked to various kava products, some serious or fatal, including with water-prepared drinks. A 2015 review argues the case reports do not prove kava was the cause and that product quality and identity were poorly controlled, so the true risk and its causes are still contested.

Is kava banned?

It depends on when and where. After case reports in 1999 and 2000, kava products were banned in Europe, and the FDA and Health Canada issued advisories in early 2002. Two German administrative courts later found the German ban inappropriate; we did not verify the current status in other countries.

Can I drink kava with alcohol?

NCCIH advises against it, because kava has sedative effects and alcohol is one of the suggested contributors to liver toxicity. Ask a clinician if you take any medicine before using kava.

Sources

Last reviewed 29 September 2026 · Next review March 2027 · How we rate evidence