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Kava
Kava — what the European monograph actually supports, what it is not for, the form and how long it is meant to be used, side effects, and the 3 medicine interactions documented for it.
This is a reference page, not a diagnosis and not a prescription. Herbal products are real pharmacology: they have effects, side effects and interactions with medicines. Tell your doctor and your pharmacist everything you take, including teas and supplements, and never stop or change a prescribed medicine because of anything you read here.
What it is
Piper methysticum G.Forst. — root and rhizome
Grouped here under Where the harm is. Regulatory position: Withdrawn, suspended or restricted as a medicine in much of Europe after reports of severe liver injury.
What the evidence supports
The registered indication: It was marketed for anxiety. It is included here as a boundary, not a recommendation.
Kava beverages have a long cultural history in the Pacific islands. The European story is different: standardised kava extracts marketed for anxiety in the 1990s were withdrawn or suspended in several countries after reports of severe hepatotoxicity, including liver failure requiring transplantation. Regulatory positions have shifted back and forth in the decades since and availability differs by country, which is exactly why an internet order is a poor way to settle the question. The awkward part of the case is that the trials suggested a genuine anxiety-reducing effect — an effective product with a rare, catastrophic harm is a much harder judgement than an ineffective one, and that is the honest shape of the kava file rather than a simple story of quackery. Preparation matters too: traditional water-based preparations of the peeled rootstock differ from the acetone and ethanol extracts that reached European shelves.
D — Popular claim unsupported, or safety dominates The better trials are negative, or the substance appears in the literature mainly for the harm it has caused.
What it is not for
Anxiety disorders, which have treatments with far better-characterised risk. Do not import it to self-treat.
Form, strength and how long
Traditional water-based root beverages; ethanol and acetone extracts in capsules, which are the preparations associated with the liver reports.
Duration. Not applicable — no European regulator is recommending a course.
No gram figure appears on this page on purpose. The plant part, the extraction solvent and the drug-to-extract ratio together define a preparation, and a number taken from one does not describe another. The reasoning is set out on the hub; the amount that applies to you is the one printed on the pack you are holding, and a pharmacist will read it with you.
Side effects
Liver injury, which is rare but has been severe and occasionally fatal. Regular heavy use causes a dry, scaly skin condition known as kava dermopathy. Drowsiness and impaired driving, markedly worsened by alcohol.
Who should avoid it
Avoid entirely with any liver disease, in pregnancy and while breastfeeding, and before driving.
Interactions with medicines
| Medicine or substance | What is described |
|---|---|
| Alcohol | The combination increases both sedation and the liver risk, and impaired driving with kava plus alcohol is documented. |
| Sleeping tablets, benzodiazepines and sedating antihistamines | Additive sedation with benzodiazepines, sleeping tablets and sedating antihistamines. |
| Anything else that stresses the liver | Anything else with a liver signal — including alcohol and several medicines — should not be stacked with it. |
The reverse view — start from the medicine rather than the plant — is in the medicine, food and alcohol interactions reference, and summarised for every herb on this site.
Sources: NIH National Center for Complementary and Integrative Health — herb fact sheets · LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (NIDDK, National Institutes of Health) · checked 2026-09-06
Frequently asked questions
What is kava used for?
It was marketed for anxiety. It is included here as a boundary, not a recommendation. Kava beverages have a long cultural history in the Pacific islands. The European story is different: standardised kava extracts marketed for anxiety in the 1990s were withdrawn or suspended in several countries after reports of severe hepatotoxicity, including liver failure requiring transplantation. Regulatory positions have shifted back and forth in the decades since and availability differs by country, which is exactly why an internet order is a poor way to settle the question. The awkward part of the case is that the trials suggested a genuine anxiety-reducing effect — an effective product with a rare, catastrophic harm is a much harder judgement than an ineffective one, and that is the honest shape of the kava file rather than a simple story of quackery. Preparation matters too: traditional water-based preparations of the peeled rootstock differ from the acetone and ethanol extracts that reached European shelves.
Does kava work?
Graded D here: The better trials are negative, or the substance appears in the literature mainly for the harm it has caused. Anxiety disorders, which have treatments with far better-characterised risk. Do not import it to self-treat.
How much kava should I take?
This reference does not print gram figures, because they do not transfer between preparations of different extract strength. What can be said honestly is the form and the duration: Traditional water-based root beverages; ethanol and acetone extracts in capsules, which are the preparations associated with the liver reports. Not applicable — no European regulator is recommending a course.
What are the side effects of kava?
Liver injury, which is rare but has been severe and occasionally fatal. Regular heavy use causes a dry, scaly skin condition known as kava dermopathy. Drowsiness and impaired driving, markedly worsened by alcohol.
Does kava interact with medicines?
Yes — documented for Alcohol, Sedatives, Liver load. Each one is described on this page, with a link to the medicine-side reference where one exists.
Others in where the harm is
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