Topic Overview

NOTE: Products containing kava have caused serious liver problems in previously healthy people. Health Canada has not licensed any kava products for sale in Canada.

What is kava?

Kava—or kava kava—is a root found on South Pacific islands. Islanders have used kava as medicine and in ceremonies for centuries.

Kava has a calming effect, producing brain wave changes similar to changes that occur with calming medicines such as diazepam (Valium, for example). Kava also can prevent convulsions and relax muscles. Although kava is not addictive, its effect may decrease with use.

Traditionally prepared as a tea, kava root is also available as a natural health product in powder and tincture (extract in alcohol) forms.

What is kava used for?

Kava's calming effect may relieve anxiety, restlessness, sleeplessness, and stress-related symptoms such as muscle tension or spasm. Kava may also relieve pain.

When taken for anxiety or stress, kava does not interfere with mental sharpness. When taken for sleep problems, kava promotes deep sleep without affecting restful REM sleep.

Kava may be used instead of prescription antianxiety drugs, such as benzodiazepines and tricyclic antidepressants. Kava should never be taken with these prescription drugs. Avoid using alcohol when taking kava.

Is kava safe?

Kava may have severe side effects and should not be used by everyone. Kava has caused liver failure in previously healthy people. You should not use kava for longer than 3 months without consulting your doctor.

Before you use kava, consider that it:

  • Should not be combined with alcohol or psychotropic medicines. Psychotropic medicines are used to treat psychiatric disorders or illnesses and include antidepressants and mood stabilizers. Alcohol exaggerates kava's sedating effect.
  • Can affect how fast you react, making it unsafe to drive or use heavy machinery.
  • May gradually be less powerful as you use it.
  • Eventually may cause temporary yellowing of skin, hair, and nails.
  • Can cause an allergic skin reaction (rare).

Long-term kava use may result in:

  • Liver problems.
  • Shortness of breath (reversible).
  • Scaly rash (reversible).
  • Facial puffiness or swelling (reversible).

Reports from Germany and Switzerland about kava causing serious liver problems have led to the recent removal of these products from shelves in Canada. Other countries have advised consumers to avoid using kava until further information is available.

In the United States, the FDA advises people who have liver disease or liver problems, or people who are taking medicines that can affect the liver, to consult a doctor or pharmacist before using products that contain kava. People who use a natural health product that contains kava and experience signs of illness should consult a doctor. Symptoms of serious liver disease include brown urine as well as yellowing of the skin or of the whites of the eyes. Other symptoms of liver disease may include nausea, vomiting, light-coloured stools, unusual tiredness, weakness, stomach or abdominal pain, and loss of appetite.

The Natural Health Products Directorate (NHPD), within the Health Products and Food Branch of Health Canada, regulates natural health products in Canada. Natural health products, including kava, must be reviewed and approved by the NHPD before they can be sold in Canada.

Always tell your doctor if you are using a natural health product or if you are thinking about combining a natural health product with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a natural health product. This is especially important for women who are pregnant or breastfeeding.

When using natural health products, keep in mind the following:

  • Like conventional medicines, natural health products may cause side effects, trigger allergic reactions, or interact with prescription and non-prescription medicines or other natural health products you might be taking. A side effect or interaction with another medicine or natural product may make other health conditions worse.
  • The way natural health products are manufactured may not be standardized. Because of this, how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form of natural health product that you buy in health food or grocery stores may not be the same as the form used in research.
  • Other than for vitamins and minerals, the long-term effects of most natural health products are not known.

Related Information


Other Works Consulted

  • Murray MT (2013). Pliper methysticum (kava). In JE Pizzorno, MT Murray, eds., Textbook of Natural Medicine, 4th ed., pp. 960–965. St. Louis: Mosby.
  • Connor KM, et al. (2006). Kava in generalized anxiety disorder: Three placebo-controlled trials. International Clinical Psychopharmacology, 21(5): 249.
  • Kava (2013). In A DerMarderosian, JA Beutler, eds., Review of Natural Products, St. Louis: Wolters Kluwer Health.


ByHealthwise Staff
Primary Medical Reviewer Adam Husney, MD - Family Medicine
Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Kathleen Romito, MD - Family Medicine

Current as ofMay 22, 2015