Kava and depression: what the research shows, and what is missing

· 6 min read

By the kava.fyi editorial team · Last updated:

Articles about kava often use the word "antidepressant." Ask which studies that label rests on, and the list turns out to be short. Below we gather what has actually been measured, and mark clearly where the evidence runs out. This article is for information only and does not replace medical advice; depression is an illness that a specialist diagnoses and manages.

Depression in numbers

According to a World Health Organization fact sheet, around 4% of the world's population experienced depression in 2023, including 5.2% of adults (4.1% of men and 6.2% of women). That is roughly 322 million people. Depression is about 1.5 times more common in women than in men, and more than 10% of women experience its symptoms during pregnancy and after childbirth. The WHO also reports that around 727,000 people died by suicide in 2021, and that suicide is the third leading cause of death in the 15 to 29 age group.

The same document describes how a depressive episode differs from ordinary mood swings: symptoms persist for most of the day, nearly every day, for at least two weeks. It also describes what effective help looks like: psychological therapies (behavioural activation, cognitive behavioural therapy, interpersonal psychotherapy, problem-solving therapy) are first line, while antidepressant medicines, SSRIs for example, are recommended for moderate and severe depression but are not needed for mild depression. No plant appears anywhere in that list. That is a useful benchmark for everything that follows.

Where the link between kava and mood comes from at all

The link has two sources. The first is pharmacology. A 2011 review by Sarris and colleagues describes kava's anxiolytic effect as arising from modulation of the GABA system, inhibition of monoamine oxidase B, and inhibition of noradrenaline and dopamine reuptake. The last two mechanisms broadly resemble how some antidepressants work, hence the temptation to carry that analogy over to a clinical effect. A mechanistic analogy, though, is not evidence of effect. We cover what kavalactones actually do separately, as well as the relationship between kava and GABA.

The second source is the overlap between symptoms. Anxiety and low mood very often occur together, so if something reduces anxiety, an improvement can also show up on depression questionnaires. That is not the same thing as an antidepressant effect in the sense used in clinical trials, where depression is the primary diagnosis and the primary endpoint.

The only study that measured depression

The most frequently cited work is the Kava Anxiety Depression Spectrum Study (KADSS) from 2009. This was a 3-week, double-blind, placebo-controlled crossover trial that recruited 60 adults with heightened generalised anxiety lasting at least a month. Participants took an aqueous kava extract at a dose of 250 mg of kavalactones a day. The primary outcome was anxiety, measured with the Hamilton Anxiety Scale (HAMA), which fell significantly more with kava than with placebo. In pooled analyses, a significant reduction was also found on the Montgomery-Åsberg Depression Rating Scale (MADRS). The authors concluded that the extract showed anxiolytic and antidepressant activity and appeared equally effective when anxiety was accompanied by depression.

Its limitations, though, need to be stated honestly:

In other words, this is one small study with anxiety as the lead condition. Most claims about "antidepressant kava" rest on it.

What the larger trials showed

Subsequent trials by the same team moved towards anxiety, not depression. In the 2013 study (75 people enrolled, 6 weeks, generalised anxiety disorder), a co-occurring mood disorder was actually an exclusion criterion, so it says nothing about depression. The largest trial, published in 2020, covered 171 people with diagnosed generalised anxiety disorder over 16 weeks and found no advantage for aqueous kava extract over placebo even for anxiety. The kava group more often reported worsened memory and tremor, and abnormal liver-test results were more frequent, though nobody met the criteria for drug-induced liver injury. A detailed review of the anxiety trials is in the article kava and anxiety.

If the largest trial did not confirm an effect on anxiety, the area where the evidence was strongest, it is hard to expect the picture to look any better for depression, where there is almost no data at all.

What the guidelines and reviews say

In 2022, the World Federation of Societies of Biological Psychiatry (WFSBP), together with the Canadian CANMAT network, published guidelines on the use of nutraceuticals and phytoceuticals in psychiatry, based solely on meta-analyses and at least two randomised trials. In unipolar depression, positive recommendations went to St John's wort (recommended), saffron and curcumin (conditionally recommended), and lavender (weakly recommended). Kava does not appear in that group at all, and for generalised anxiety disorder it was rated "not recommended." The authors noted that a lack of data does not mean a lack of efficacy, but also that plant-based preparations should be used within standard medical care, especially in more severe disorders.

For balance: a 2022 review by Moragrega and Ríos, covering 95 clinical trials of medicinal plants for depression from 2000 to 2020, lists kava among six plants with the most substantial evidence, alongside saffron, turmeric, St John's wort, ginkgo and rhodiola. It is worth remembering, though, that the only kava trial to measure depression is the KADSS study described above, so this is more a pointer than a confirmation.

Caution: medicines, alcohol and the liver

Someone with depression is often taking medication, and this is the most important practical point in this article. The 2011 review recommends avoiding combining kava with alcohol, exercising caution with other psychotropic medicines, and routine liver tests for people using kava regularly. The 2016 FAO/WHO report adds that kavalactones inhibit certain cytochrome P450 enzymes, which can alter the metabolism and toxicity of medicines taken alongside it, and flags drug interactions as one of the knowledge gaps needing research. Kava also inhibits monoamine oxidase B. For these reasons, the decision to combine kava with any pharmacotherapy should be left to the treating doctor. We cover the history of the liver allegations in the article kava and the liver.

Summary

The state of evidence on kava and depression is thin, and can be summed up in a few sentences. Kava's mechanism of action touches on systems linked to mood. One small 2009 study, conducted in people with anxiety, additionally noted an improvement on a depression scale. No trial has tested kava in people with depression as the primary diagnosis, the largest anxiety trial, from 2020, came back negative, and current guidelines do not list kava among the plant-based preparations with documented effects on depression. If low mood or a loss of ability to feel pleasure persists for most of the day for more than two weeks, the right place to go is a doctor or psychotherapist, not a plant. We write about the state that is not yet depression, but is not wellbeing either, in the article on languishing.

Sources

  1. WHO: Depressive disorder (depression), arkusz informacyjny [fact sheet] https://www.who.int/news-room/fact-sheets/detail/depression
  2. Sarris J, LaPorte E, Schweitzer I (2011): Kava: a comprehensive review of efficacy, safety, and psychopharmacology. Aust N Z J Psychiatry https://pubmed.ncbi.nlm.nih.gov/21073405/
  3. Sarris J i wsp. (2009): The Kava Anxiety Depression Spectrum Study (KADSS): a randomized, placebo-controlled crossover trial using an aqueous extract of Piper methysticum. Psychopharmacology https://pubmed.ncbi.nlm.nih.gov/19430766/
  4. Sarris J i wsp. (2013): Kava in the treatment of generalized anxiety disorder: a double-blind, randomized, placebo-controlled study. J Clin Psychopharmacol https://pubmed.ncbi.nlm.nih.gov/23635869/
  5. Sarris J i wsp. (2020): Kava for generalised anxiety disorder: A 16-week double-blind, randomised, placebo-controlled study. Aust N Z J Psychiatry https://pubmed.ncbi.nlm.nih.gov/31813230/
  6. Sarris J i wsp. (2022): Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: WFSBP and CANMAT Taskforce. World J Biol Psychiatry https://pubmed.ncbi.nlm.nih.gov/35311615/
  7. Moragrega I, Ríos JL (2022): Medicinal Plants in the Treatment of Depression. II: Evidence from Clinical Trials. Planta Med https://pubmed.ncbi.nlm.nih.gov/34157753/
  8. FAO/WHO (2016): Kava: a review of the safety of traditional and recreational beverage consumption. Technical Report, Rome https://openknowledge.fao.org/server/api/core/bitstreams/f97fbe5f-244e-4301-be2a-03ac39ef630b/content