Kava has been used in Pacific island communities for thousands of years. In places like Fiji, Vanuatu, and Tonga, drinking kava is a social and ceremonial tradition, much like wine or beer in Western cultures. The root produces a mild sedative effect that leaves drinkers feeling relaxed without impairing their thinking the way alcohol does.

In the 1990s, kava extracts became popular in Europe and North America as a natural alternative to prescription anxiety medications. Then came reports of liver damage, regulatory warnings, and outright bans in several countries. Germany banned kava in 2002 but lifted the restriction in 2015 after courts ruled the evidence insufficient. The regulatory back-and-forth left many people confused about whether kava is actually safe.

I’ve gone through the clinical research to sort out what we actually know about kava’s benefits and risks.

What is kava?

Kava (Piper methysticum) is a perennial shrub native to the western Pacific islands. The word “kava” comes from Polynesian languages and means “bitter” or “pungent”, which accurately describes the taste.

The plant’s underground stems (rhizomes) and roots contain the active compounds called kavalactones. At least 18 different kavalactones have been identified, with six of them accounting for roughly 96% of the total kavalactone content in most preparations [1]. These compounds interact with GABA receptors in the brain, which explains kava’s relaxing effects.

Traditional preparation involves grinding the root and mixing it with water to create a drink. Commercial supplements typically use standardised extracts, with dosages expressed as total kavalactone content (usually 70-250 mg per day).

What are the potential benefits of kava?

1. Anxiety reduction

This is kava’s main selling point, and it’s the benefit with the most research behind it. Generalised anxiety disorder affects about 6% of people at some point in their lives [2]. The constant worry, restlessness, difficulty concentrating, and sleep problems can seriously interfere with daily functioning.

A Cochrane review examined 12 randomised controlled trials comparing kava with placebo for anxiety [3]. The pooled analysis found a statistically significant reduction in anxiety scores favouring kava. However, the effect size was modest, and the authors noted considerable variation between trials.

The most consistent positive results come from trials using the standardised extract WS 1490 at doses of 100-200 mg kavalactones daily. A 4-week German trial with 101 patients found that kava extract (70 mg kavalactones three times daily) significantly reduced anxiety compared to placebo [4]. Participants reported improvements in worry, tension, and overall wellbeing.

My honest assessment: the evidence suggests kava probably helps with anxiety, but don’t expect dramatic results. The effect appears comparable to some prescription medications, but without the sedation and cognitive impairment that benzodiazepines cause. If you’re dealing with mild to moderate anxiety and prefer trying a herbal option before medications, kava might be worth discussing with your doctor.

For those with more severe anxiety, see our guide on overactive bladder, which covers the anxiety connection, or our article on L-theanine, another calming supplement with fewer safety concerns.

2. Sleep quality improvement

Sleep problems and anxiety often go together. If kava reduces anxiety, it makes sense that it might also help with sleep.

A 22-week study followed 24 patients with stress-related insomnia [5]. Participants received kava extract (LI 150) and showed improvements in both stress levels and sleep quality. The catch? This was an uncontrolled study without a placebo group, so we cannot rule out placebo effects.

A better-designed 4-week randomised trial tested kava extract (WS 1490) in patients with anxiety-related insomnia [6]. The kava group showed significantly better sleep quality than placebo. Participants fell asleep faster and reported feeling more rested upon waking.

Here’s my take: if your sleep problems stem from anxiety and racing thoughts, kava might help by addressing the underlying worry. If your insomnia has other causes (sleep apnoea, chronic pain, poor sleep hygiene), kava probably won’t make much difference.

For more on sleep aids, see our articles on melatonin, valerian, and GABA.

3. Cognitive function

This one is more speculative. Some traditional kava users claim it enhances mental clarity without the “foggy” feeling that comes from alcohol or sedatives.

A small crossover study tested kava extract in 12 healthy men over 5 days [7]. Compared to placebo, kava improved performance on a visual recognition task and altered brain wave patterns (event-related potentials) in ways that suggested enhanced attention processing.

I should be honest here: 12 participants over 5 days tells us very little. The cognitive benefits of kava, if they exist, remain largely unproven. I wouldn’t take kava specifically hoping to boost mental performance.

Side effects and safety concerns

The elephant in the room with kava is liver toxicity. Between 1999 and 2002, health authorities received reports of liver damage (including cases requiring transplants and some deaths) in people using kava products [8].

This led to bans or restrictions in Germany, the UK, France, and several other countries. However, the evidence linking kava directly to liver damage has always been weak:

Traditional use patterns: Pacific islanders have consumed kava for centuries without epidemic liver disease. A World Health Organisation review noted that traditional aqueous (water-based) preparations appear much safer than the acetone or ethanol extracts that became popular in Western supplements [9].

Confounding factors: Many reported cases involved people who were also drinking alcohol, taking other medications, or using products of questionable quality. Some “kava” products were later found to contain adulterants or parts of the plant (leaves, stems) that shouldn’t have been included.

Regulatory reversal: Germany lifted its kava ban in 2015 after a Federal Administrative Court ruled that the evidence for hepatotoxicity was insufficient to justify the restriction [10].

This doesn’t mean kava is completely safe. A few points are worth noting:

Some individuals may have genetic variations that make them susceptible to kava-induced liver injury
The quality and composition of kava products varies enormously
Traditional preparations (water extraction of root/rhizome only) appear safer than concentrated solvent extracts
Combining kava with alcohol significantly increases risk

Other reported side effects include headache, dizziness, drowsiness, stomach upset, diarrhoea, dry or scaly skin (with heavy long-term use), and temporary hearing changes.

Safety precautions (7 contraindications)

Pregnancy and breastfeeding: No safety data exists for these populations. The kavalactones may cross the placenta and pass into breast milk, so avoidance is prudent.
Liver disease: Anyone with existing liver problems (hepatitis, cirrhosis, fatty liver disease) should not use kava. If you’ve had elevated liver enzymes for any reason, discuss this with your doctor before considering kava.
Alcohol use: Do not combine kava with alcohol. This combination sharply increases the risk of liver damage and enhances sedation to dangerous levels.
Activities requiring alertness: While kava is less impairing than alcohol or benzodiazepines, a driving study found that kava extract could slightly affect attention and reaction time [11]. Exercise caution with driving or operating machinery, especially when starting kava or increasing doses.
Parkinson’s disease: Case reports suggest kava may worsen Parkinson’s symptoms [12]. The mechanism isn’t fully understood, but if you have Parkinson’s disease, avoid kava entirely.
Before surgery: Stop kava at least two weeks before any scheduled surgery. Kava may interact with anaesthesia and prolong sedation. It may also affect how your liver metabolises other drugs given during the perioperative period.
Drug interactions: Kava is metabolised by cytochrome P450 enzymes and may interact with numerous medications. This is a partial list of drugs that may interact with kava:
- Benzodiazepines (diazepam, alprazolam) – enhanced sedation
- Antidepressants (fluoxetine, amitriptyline) – altered metabolism
- Blood thinners (warfarin) – potential bleeding risk
- Pain medications (codeine, morphine) – enhanced sedation
- Blood pressure medications (beta-blockers, calcium channel blockers)
- Statins (lovastatin) – increased drug levels
- Immunosuppressants (ciclosporin)
- Antifungals (ketoconazole)
- Antibiotics (erythromycin)
If you take any regular medications, discuss kava use with your pharmacist or doctor.

How to choose a kava product

If you decide to try kava despite the uncertainties, product quality matters:

Look for extracts made from the root or rhizome only (not leaves, stems, or bark)
Water-based extracts (aqueous) appear safer than ethanol or acetone extracts
Choose products standardised to kavalactone content
Avoid products with unclear sourcing or quality control
The standardised extracts used in research (WS 1490, LI 150) have the most safety data

Typical research doses range from 70-250 mg of kavalactones daily, divided into two or three doses. Don’t exceed these amounts.

My bottom line

Kava probably works for anxiety. The evidence isn’t overwhelming, but multiple trials show modest benefits over placebo. For some people with mild to moderate anxiety who want to avoid prescription medications, it’s a reasonable option to discuss with their doctor.

The liver safety question remains unresolved. Traditional water-based preparations seem safe based on centuries of Pacific island use. Western solvent-based extracts are more uncertain. The risk appears low but not zero, and certain individuals may be more susceptible.

If you try kava:

Use water-based root extracts only
Don’t drink alcohol
Get your liver function tested before starting and again after a few weeks
Stop immediately if you develop fatigue, appetite loss, dark urine, or yellowing of eyes/skin

For related reading, you might also be interested in our articles on ashwagandha, another adaptogen used for stress and anxiety, or melatonin for sleep-specific concerns.

3 benefits and side effects of valerian – Another herbal sedative with research for sleep and anxiety
5 benefits and side effects of L-theanine – An amino acid from tea that promotes relaxation without drowsiness
4 benefits and side effects of GABA – The calming neurotransmitter and supplement form

References

Teschke R, et al. Kava hepatotoxicity: a clinical review. Ann Hepatol. 2010;9(3):251-265. PMID: 20720265
Ruscio AM, et al. The epidemiology of generalized anxiety disorder. Epidemiol Psychiatr Soc. 2017;26(5):445-456. PMID: 28766125
Pittler MH, Ernst E. Kava extract for treating anxiety. Cochrane Database Syst Rev. 2003;(1):CD003383. PMID: 12535473
Volz HP, Kieser M. Kava-kava extract WS 1490 versus placebo in anxiety disorders: a randomized placebo-controlled 25-week outpatient trial. Pharmacopsychiatry. 1997;30(1):1-5. PMID: 9065962
Wheatley D. Stress-induced insomnia treated with kava and valerian: singly and in combination. Hum Psychopharmacol. 2001;16(4):353-356. PMID: 12404572
Lehrl S. Clinical efficacy of kava extract WS 1490 in sleep disturbances associated with anxiety disorders. J Affect Disord. 2004;78(2):101-110. PMID: 14706720
Sarris J, et al. The effects of kava beverage on event-related potentials: a randomized, placebo-controlled crossover study. J Clin Psychopharmacol. 2013;33(6):788-792. PMID: 24100785
Teschke R, et al. Kava hepatotoxicity: comparison of aqueous, ethanolic, acetonic kava extracts and kava-herbs mixtures. J Ethnopharmacol. 2009;123(3):378-384. PMID: 19501271
World Health Organization. Assessment of the risk of hepatotoxicity with kava products. WHO; 2007.
Sarris J, et al. Kava: a comprehensive review of efficacy, safety, and psychopharmacology. Aust N Z J Psychiatry. 2011;45(1):27-35. PMID: 21073405
Moss J. Kava and driving: a real concern? J Altern Complement Med. 2015;21(6):370-371. PMID: 26337520
Schelosky L, et al. Kava and dopamine antagonism. J Neurol Neurosurg Psychiatry. 1995;58(5):639-640. PMID: 7745420