Supplement

Kava

Herbs · Piper methysticum, kava pepper, kawa, kava-kava, kavalactones, kavain

Kava is the root of a pepper shrub from the South Pacific, where the drink made from it has been part of social life for generations. In Europe, kava was for some years a herbal remedy for anxiety, until reports of liver damage took it off the market in several countries. Today it is prescription-only in Germany.

In short

Kava has been studied for anxiety in several controlled trials: a Cochrane review of 11 double-blind trials found less anxiety than with placebo, and a 2013 study confirmed this in generalized anxiety disorder with a medium effect. The largest and longest trial, with 171 people over 16 weeks, found no benefit in 2020, but did find abnormal liver values more often. Because of reported liver damage up to transplants and deaths, the EMA considers the benefit-risk balance unfavorable. In Germany, kava rhizome, its preparations and kavain are prescription-only; there is no authorization as a food.

What kava is and how it works

Kava is the rhizome of Piper methysticum, a plant of the pepper family. In many countries of the South Pacific, the drink made from it is part of ceremonies and everyday life and an important trade good. The kavalactones, including kavain, are considered the active ingredients. The effect is described as relaxing and anxiety-relieving.

How kava acts in the brain has only partly been measured. In an imaging study with 37 people with generalized anxiety disorder, the messenger substance GABA in the anterior cingulate gyrus fell more after 8 weeks of kava than under placebo. This change was not related to the severity of anxiety. If you are comparing herbal alternatives, you will find similar questions for ashwagandha, L-theanine or GABA.

What is well supported

Less anxiety in the Cochrane review. 11 double-blind, placebo-controlled trials with 645 participants; in 6 trials with 345 participants, the Hamilton Anxiety Scale fell by 5.0 points more than under placebo. Side effects in these trials were mild, transient and rare.
A positive finding in generalized anxiety disorder. In a 6-week study with 75 people, anxiety fell more than under placebo (d = 0.62), and even more clearly in moderate to severe disorder (d = 0.82). At the end, 26 percent were in remission, compared with 6 percent under placebo.
Long use. Kava has been drunk in the South Pacific for generations and has a firm social and economic role there.

What the studies show

Cochrane 2003: kava against placebo for anxiety

The review searched for all double-blind, placebo-controlled trials with pure kava extract and found 11 with 645 participants, with study durations of 1 to 24 weeks. Six trials used the same anxiety scale; pooled, this gave an advantage of 5.0 points (1.1 to 8.8). The authors considered kava an effective treatment for anxiety symptoms and relatively safe in the short term, but called for more data on long-term safety.

Sarris 2013: generalized anxiety disorder over 6 weeks

75 people with generalized anxiety disorder without a concomitant affective disorder received an aqueous kava extract or placebo; 58 were analyzed. Anxiety fell more with kava (p = 0.046, d = 0.62). Apart from somewhat more headaches, there were no differences in side effects or liver values.

Sarris 2020: the large study over 16 weeks

171 people with generalized anxiety disorder who were not taking any medication received kava extract or placebo for 16 weeks. Anxiety actually fell slightly more under placebo, by 1.37 points (not significant); 17.4 percent were in remission with kava and 23.8 percent with placebo. Tremor and memory problems occurred more often with kava, and abnormal liver values were more frequent; no one had herb-induced liver injury. The authors suggest that kava helps more with temporary tension than with a diagnosed anxiety disorder.

Meta-review 2021: herbal remedies in psychiatry

A review of 9 meta-analyses with data from 5,927 people rated St. John’s wort, curcumin, saffron and ginkgo as supported for certain uses. For kava, it concluded that it is not effective in diagnosed anxiety disorders.

Where the data stop

Diagnosed anxiety disorder. The largest and longest trial found no benefit, and the 2021 meta-review rates kava as not effective for this. The positive data come mainly from older, shorter studies.
Long-term safety. The studies lasted at most 24 weeks. There are no controlled data for longer use.
Cause of the liver damage. Whether the kavalactones themselves, certain extraction methods or contaminated raw material are responsible has not been clarified. Traditional aqueous preparations have also been linked to liver damage.
Mechanism. The GABA change in the brain was not related to anxiety; how kava works remains open.

Status, approval and legal

In Germany, kava-kava rhizome and its preparations as well as kavain are listed in Annex 1 of the German Prescription Drug Ordinance (Arzneimittelverschreibungsverordnung) and are therefore prescription-only; only certain homeopathic preparations are exempt. In 2017 the European Medicines Agency declined to issue an EU monograph for herbal medicines made from kava: the requirements for traditional or well-established use were not met, and the benefit-risk balance was unfavorable.

Kava is not authorized as a food in the EU: the European Commission’s Novel Food Catalogue contains no entry for Piper methysticum (checked October 7, 2026). If kava powder or kava drinks are offered to you as food, there is no EU-level authorization for this.

Safety

The EMA refers to spontaneously reported liver damage including liver failure with liver transplants and deaths, to the withdrawal of products in several EU countries and to indications of carcinogenic potential in animal studies. A 2012 analysis shows that traditional aqueous preparations have also been linked to liver damage, and discusses poor-quality raw material, for example due to mold toxins, as a possible cause.

In the controlled trials, side effects were mostly mild. In the 16-week trial, however, abnormal liver values, tremor and memory problems occurred more often. In the BK-Score, safety stands at 5 out of 10: the risks are described, but their cause and frequency have not been reliably clarified. This text is information and does not replace medical advice.

BK-Score Supported, with caveats

Human evidence		6
Mechanism		4
Safety data		5
Hype gap		5
Track record of use		8

Evidence 6, because a Cochrane review of 11 double-blind trials with 645 participants finds less anxiety than with placebo (Pittler and Ernst 2003) and a study with 75 people with generalized anxiety disorder confirms this (Sarris 2013), but the largest and longest trial, with 171 people over 16 weeks, shows no benefit (Sarris 2020) and a meta-review rates kava as not effective in diagnosed anxiety disorders (Sarris 2021). Mechanism 4, because the kavalactones are named as the active ingredients and a change in brain GABA has been measured in humans (Savage 2023), without it being related to anxiety. Safety 5, because studies of up to 24 weeks show predominantly mild side effects, but the 16-week trial found abnormal liver values more often and the EMA refers to reported liver damage up to transplants and deaths whose cause has not been reliably clarified (Teschke 2012). Hype 5, because kava is regarded as a natural remedy for anxiety, which fits the early studies but no longer holds for diagnosed anxiety disorder. Use 8, because kava has been drunk in the South Pacific for generations and was on the market in Europe as a medicine for years. Mixed direction: positive short studies and a Cochrane review stand against a negative large trial and unresolved liver risks.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless. “Track record of use 9” means used long and widely – that is not proof of efficacy.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about kava

Does kava help against anxiety?

In short studies, yes: a Cochrane review of 11 trials found less anxiety than with placebo, and a study with 75 people with generalized anxiety disorder confirmed this. The largest trial, with 171 people over 16 weeks, however, found no benefit. For diagnosed anxiety disorder, the benefit is therefore not established.

Is kava harmful to the liver?

There are reported cases of liver damage up to liver transplants and deaths, which the EMA cites. In the 16-week trial, abnormal liver values were more frequent under kava; no liver injury occurred. How common severe damage is and what causes it has not been clarified.

Is kava legal in Germany?

Kava rhizome, its preparations and kavain are prescription-only in Germany. Kava is not authorized as a food in the EU; the Novel Food Catalogue contains no entry for it.

Why do the studies contradict each other?

The positive data come mainly from shorter studies; the large negative trial ran for 16 weeks in people with diagnosed generalized anxiety disorder. The authors suggest that kava helps more with temporary tension than with an anxiety disorder. Different extracts may also play a role.

How does kava work?

The kavalactones are considered the active ingredients. In one study, the messenger substance GABA fell after 8 weeks in a brain region that plays a role in anxiety. However, this was not related to the severity of anxiety; the exact mechanism is open.

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Sources

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-07.