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Question mark: This treatment has not been properly researched. It is not possible to say whether they are useful or not.


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  • 3 smiliesThese treatments are very useful. They are strongly supported as effective by scientific evidence.
  • 2 smiliesThese treatments are useful. They are supported by scientific evidence as effective, but the evidence is not as strong.
  • 1 smileyThese treatments are promising and may be useful. They have some evidence to support them, but more evidence is needed to be sure they work.
  • No smiley On the available evidence, these treatments do not seem to be effective.
  • Question markThese treatments have not been properly researched. It is not possible to say whether they are useful or not.
  • Exclamation MarkSafety or other concerns have been raised for the use of these treatments.

What is it?

Kava (scientific name: Piper methysticum) is a type of plant from the pepper family. The roots of the plant are used to make a tea (or other supplements) which has sedative effects. Kava is traditionally consumed by people from certain cultures in the Pacific Islands.

How does it work?

Kava contains components called kavalactones. These can affect the levels of chemical messengers (neurotransmitters) in the brain which are thought to play a role in depression and anxiety. They also affect the speed of signals in the brain. Kava has a calming and sedative effect when ingested. This can reduce symptoms of anxiety, which commonly co-occurs with depression.

Is it effective?

There is very little scientific evidence on kava for the treatment of depression.

One study treated people who had depression and anxiety with kava for one week, and then with a placebo for one week (some participants received the placebo first, others received the treatment first). Participants had a greater reduction in depression symptoms after the week of taking the kava treatment.

Another study treated people who had depression and anxiety with both kava and St John’s Wort. Only some people who received the kava treatment experienced a greater reduction in depression symptoms compared to people who received a placebo (dummy) treatment. It is also possible that any positive effects were due to the St John’s Wort, which research has found to be quite effective at treating depression. 

Kava had not been studied as a treatment for people who only have depression and no symptoms of anxiety. The long term effects of kava have also not been studied. More studies of better quality are needed to understand if kava could be helpful in treating depression.

Are there any disadvantages?

Kava can be toxic to the liver. It should not be taken by people who have existing liver damage. Because of this, the Therapeutic Goods Administration in Australia has placed restrictions on the sale and importation of kava. While possession of small amounts of kava is legal in most areas of Australia, there may be restrictions on the sale and use of kava in your area.

Side effects of kava can include a numb mouth and throat, sleepiness, reduced appetite, nausea, and loss of muscle control. Prolonged use can lead to a condition called “kava dermatitis”, which causes a dry, scaly rash. Because kava has sedative effects, it should not be consumed before driving or operating heavy machinery.

Kava may have negative interactions with other herbal supplements and prescribed medications. Taking kava alongside other drugs which have sedative effects (such as alcohol and benzodiazepines) can be particularly dangerous. You should always talk with your doctor or pharmacist if you are thinking of taking kava and make sure you discuss potential interactions with other medications or supplements you are taking.

Kava should not be taken by pregnant or breastfeeding women.

Where do you get it?

Kava can be purchased as a tablet supplement and in teabags from some online herbal retailers.


Given the lack of evidence on kava, it cannot be recommended as a treatment for depression. Safety concerns have been raised for the use of this supplement. Please consult a doctor or pharmacist before using kava.

In Australia, the possession and sale of kava subject to restrictions. The laws and penalties regarding the possession and use of kava vary from state to state.

Key references

  • Sarris J, Kavanagh DJ, Byrne G, Bone KM, Adams J, Deed G. The Kava Anxiety Depression Spectrum Study (KADSS): a randomized, placebo-controlled crossover trial using an aqueous extract of Piper methysticum. Psychopharmacology. 2009; 205(3):399-407.
  • Sarris J, Kavanagh DJ, Deed G, Bone KM. St. John's wort and Kava in treating major depressive disorder with comorbid anxiety: a randomised double-blind placebo-controlled pilot trial. Human Psychopharmacology. 2009; 24(1):41-8.

Last updated and reviewed: 28 August 2023