Kava Dangers: Does Kava Damage the Liver?

illustration of a Polynesian guys with danger and caution signs

There are a lot of rumors circulating about the dangers of kava.

Some reports suggest kava can cause liver damage, addiction, or kidney disease — all of which would clearly outweigh the benefits of using the herb in the first place.

In this article, we’re going to discuss why you shouldn’t worry about these dangers, where these rumors came from, why kava remains banned in a handful of countries to this day, and what the real safety profile of kava looks like.

Let’s get into it.

What is Kava?

Kava is a medicinal herb from the islands of the pacific ocean. It’s been used by local cultures on these islands for hundreds, potentially even thousands, of years.

There are a few different species of kava, but by far the most commonly used for ceremonial and social use is Piper methysticum, and it’s the most common variety found in supplements

Other species of the plant such as Piper wichmanii are sometimes used but are generally reserved for specific medicinal use by traditional healers on some of the islands in the South Pacific. This species of kava has much more likelihood of producing side-effects like nausea or intoxication.

Kava is traditionally used by masticating (chewing) the roots into a pulp, before mixing with water for several minutes. The root pieces are then strained out and the resulting muddy fluid is consumed.

Modern methods use a dried, powdered root instead — which produces the same result. You can also find kava in the form of capsules, tinctures, or pastes as well.

What Does Kava Feel Like?

After just a few cups of kava tea, users begin to feel a wave of relaxation — All the stress, worry, and discomfort you may have felt before begins to slip away. The muscles relax, the mind settles, and you start to feel a wave of euphoria drifting in.

The more kava you drink, the stronger these sensations become — eventually leading into fatigue or sedation with the higher doses.

Depending on how you intend to use kava will determine the amount you should take, as well as the type of kava you should use.

Heady Kava, Heavy Kava, and Balanced Kava

If your goal of using kava is to support your sleep should look for something described as “heavy.” These kavas will be fairly strong and provide more effects on the body than the mind. They produce powerful muscle-relaxant effects and make the body feel heavy like you’re melting into the ground.

On the other hand, if you want to use kava in a social setting, “heady” kava is better. These kavas aren’t as heavy and tend to produce stronger effects on the psyche. They’re suited for stress, anxiety, or for promoting creative thought processes. Heady kava is excellent for daytime use or for drinking with friends.

The final type of kava is referred to as “balanced” kava — which is an even mix of heady and heavy sensations. This kava is the most well-rounded and can be used for both sleep, and stress. Higher doses are going to be sedating like a heavy kava, while smaller doses may be mildly euphoric like a heady kava.

Is Kava Dangerous?

Now that we’ve covered what kava is, and a little bit about the different types of kava you can buy, we’re on to the main question of this article — “is kava dangerous?”

The simple answer to this question is no — with some exceptions.

Kava has been put through extensive clinical trials involving hundreds of patients, conducted over several weeks of study, using relatively high doses of kava. Over the past ten years of research, none of these studies suggested that kava was inherently dangerous.

So where did the rumors surrounding the dangers of kava come from?

Prior to 1988, kava was established as a safe and effective herbal remedy for symptoms of anxiety, stress, and sleep disorders.

Everything changed after German and Swiss researchers began publishing case reports involving liver toxicity in their patients after using kava extract. These case reports eventually lead to a ban in Switzerland and Germany, and sweeping bans throughout the rest of Europe, Australia, New Zealand, and North America.

These case reports have since been discredited and the ban overturned.

The case studies mentioned above were found to involve the use of kava alongside other medications with known liver toxicity — which isn’t enough evidence to prove kava is dangerous or can cause liver damage on its own. It merely suggests that kava can’t prevent liver damage caused by other toxic medications.

Most of the bans on kava have since lifted after three decades of research suggesting the herb wasn’t nearly as dangerous as initially thought.

Is There Evidence Kava Is Safe?

Devout kava researchers Vincent Lebot, Mark Merlin, and Lamont Lindstrom provide an in-depth analysis of kava-drinking cultures of the Pacific islands in their book — Kava: The Pacific Elixir.

Pacific islanders consume a lot of kava — in some places, as many as 80% of men and 20% of women consume high quantities of kava on a daily basis — often exceeding more than 50 grams of kava daily.

Many of these island societies submit disease statistics and data to the World Health Organization — so if kava consumption was dangerous, there should be obvious statistical data indicating kava consumption in these regions — but there isn’t.

In the table below, we look at the data provided by the World Health Organization for the life expectancy of some of the world’s most frequent kava consumers — Vanuatu, Samoa, and Tonga. We’ll compare the life expectancies of these countries with other countries of similar economic stature — and the United States.

There’s no obvious reduction in longevity in these countries compared to others within a similar economic standing (based on GDP per capita).

Comparing the WHO Data of Kava Drinking Societies vs. Non-Kava Drinking Societies

Country Kava Drinkers? Life Expectancy GDP Per Capita (USD) Sources
United States No 79 $59,531.66 Source
Peru No 76 $6,571.93 Source
Samoa Yes 75 $4,360.75 Source
Nigeria No 75 $1,968.56 Source
Paraguay No 74 $4,365.53 Source
Tonga Yes 73 $3,944.25 Source
Vanuatu Yes 72 $3,123.61 Source
Trinidad and Tobago No 72 $16,145.18 Source
Russia No 72 $10,743.10 Source
Myanmar No 67 $1,298.88 Source
Pakistan No 67 $1,547.85 Source

As you can see, there’s no clear pattern with kava drinking societies compared to non-kava drinking societies. There are other factors affecting lifespan, like financial status, conflict, and the presence of tropical diseases that have a much larger impact on a society.

Oceana — Kava’s Native Range

Scientific Research On Kava Safety

On top of traditional and anecdotal reports, there’s plenty of evidence provided by scientific research that demonstrates the safety of kava.

One study, in particular, looked at the safety profile of using kava alongside alcohol [2]. Even with the combined effects of alcohol and 210 mg of kavalactones in a standardized extract (WS 1490®) — researchers noted a lack of negative side-effects or interactions.

Another clinical trial compared the effects of kava extracts and benzodiazepine and tricyclic medications on their effectiveness — as well as safety [3]. Researchers concluded that kava was a viable alternative to benzodiazepines and displayed none of the tolerance formation the pharmaceutical medications did.

There have been plenty of other studies with similar results — suggesting kava as a safe alternative to pharmaceuticals used for the same applications.

In the next section, we’ll cover a few cases where kava may actually be dangerous.

When is Kava Dangerous?

Although kava is widely considered a safe supplement — there are some situations where kava may be dangerous.

1. Liver Disease

The early media scares of the late 1980s and early 90s suggesting a single dose of kava would cause your liver to shut down are long behind us. The vast majority of people using kava experience little to no side-effects at all.

However, people with existing liver disease, or who are taking other drugs that affect the liver or kidneys should avoid using kava altogether.

The research suggesting kava damages the liver may have had the extent of the effects wrong, but the mechanisms weren’t far off. The active kavalactones in the plant are processed by the liver — which can place extra stress on this critical organ.

A healthy liver is well-equipped to handle this stress — in fact, the liver handles a similar strain on a daily basis, especially if you consume alcohol, smoke cigarettes, drink coffee, take medications, or use other health supplements.

So if your liver is already run-down through underlying health disorders, or you’re taking other medications that place their own stress on the liver — it’s possible you may push it too far.

Some Examples of Conditions To Avoid Kava

  • Hepatitis
  • Fatty liver disease (NAFLD & AFLD)
  • Metabolic syndrome
  • Liver parasites
  • Portal hypertension
  • Cirrhosis
  • Reye’s syndrome
  • Wilson’s disease
  • If you’re taking medications with known liver toxicity (talk to your doctor)

2. GABAergic Medications (Anti-Anxiety Meds)

The main mechanisms kava uses to exert many of its effects are through a neurotransmitter known as GABA. This compound is responsible for slowing neurological activity down and regulating the parasympathetic nervous system (PNS) — which controls our rest and digest processes. It’s what helps us relax, sleep, and digest our food.

Many medications designed to treat anxiety, muscle tension, and sleep disorders work through the GABA system. The combined effect of kava and these medications could be dangerous by causing too strong of an effect — resulting in side-effects.

Common GABAergic Medications Include:

  • Amytal (amobarbital)
  • Ativan (lorazepam)
  • Butisol (butabarbital)
  • Dalmane (flurazepam)
  • Halcion (triazolam)
  • Klonopin (clonazepam)
  • Librium (chlordiazepoxide)
  • Nembutal (pentobarbital)
  • Restoril (temazepam)
  • Valium (diazepam)
  • Xanax (alprazolam)

Excessive GABAergic Effects Can Cause the Following Side-Effects:

  • Fatigue/Sedation
  • Confusion
  • Memory loss
  • Blackouts
  • Muscle weakness
  • Slowed breathing
  • Slurred speech
  • Blurred vision

Always talk with your doctor if you’re using any medications for sleep, anxiety, stress, or muscle spasms and wish to try kava.

What Are the Side-Effects of Kava?

Kava has a few side-effects of its own — most of which are mild in nature and can be alleviated by taking smaller doses the next time or using a different strain of kava.

The two main forms of kava to be aware of are Noble varieties and Tudei varieties.

Noble kava has few side-effects, even in larger doses. The most common side-effect is sedation, nausea, and dizziness — but this will also depend highly on the individual strain used.

The other form, Tudei kava, is rarely used recreationally due to the high incidence of side-effects. This form of kava often produces nausea, vomiting, dizziness, headaches, confusion, and a feeling of drunkenness — but not the good kind. Only the most experienced kava users should attempt to use this form of kava.

Common side-effects of kava include:

  • Dilated pupils
  • Facial puffiness
  • Fatigue
  • Headaches
  • Indigestion
  • Lightheadedness
  • Visual disturbances

How to Stay Safe While Drinking Kava

There are a few steps you can take to make sure you avoid danger when using kava — especially for the first time. Let’s cover them in brief:

1. Start With a Small Dose of Kava

There’s always a small chance you may be allergic to kava or have another sensitivity to it. In order to avoid having a severe reaction, it’s a wise idea to take only a small amount for your first time to see how it affects your body. If after 2 hours you don’t feel any negative effects, you may choose to take more.

A small dose of kava usually means a sip of kava tea or half a kava capsule if you can break it in half. Try to take about half of the recommended dosage listed on the package for the first dose.

2. Don’t Take Kava Alongside Drugs or Medications

As we spoke about above, kava may interact with other drugs or medications — especially those that interact with the GABA receptors, such as benzodiazepines or alcohol.

Other drugs may interact with kava indirectly, either by competing for the same pathway in the liver or forming secondary compounds with the kavalactones in the gut or bloodstream.

3. Drink Plenty of Water

Once the kavalactones are processed by the liver, they need to be filtered out of the blood via the kidneys. This can use up a lot of your water supply and cause you to become dehydrated if you don’t replenish the fluid. This is exasperated by the sedative effects of kava.

If you fall asleep — you may be going another 6-8 hours without a drink — leaving you with dehydration symptoms in the morning that can feel similar to a hangover.

Keep a bottle of water nearby and take frequent sips to help minimize the chances of experiencing side-effects.

4. Talk To Your Doctor Before Using Kava if You Have Other Health Conditions

If you have any underlying health issues, a history of allergies, or are taking any medications — it’s a good idea to speak with your doctor before using kava.

Your doctor will be able to give you an educated assessment on whether or not kava is an appropriate supplement for your body or not.

5. Take A Break Sometimes

As with any supplement, it’s wise to take some time off using kava. This helps to resist any chances of tolerance formation to the compound and gives your body time to clear out any of the active compounds that may be sticking around for too long.

If you use kava frequently, you may choose to take every third day off, or every third week off. Both will have a similar result so it just depends on your preference.

Concluding Thoughts: Is Kava Dangerous?

With talks of kava causing liver failure or addiction, it’s no wonder people are questioning whether or not kava is dangerous.

These earlier claims struck enough fear into the people of Switzerland to ban it, leading others around the world to follow suit.

Only over the past few years have these laws been revoked. Dozens of research papers, including a handful of clinical trials have all concluded that kava doesn’t cause liver damage in normal doses.

With that said, kava may become dangerous if used in conjunction with other compounds that damage the liver or interact with GABA in the brain. The combined effect may increase the chances of producing negative side-effects from these other compounds — rather than from the kava itself.

Although kava is inherently safe, we recommend that you speak with your doctor if you’re unsure about using it — especially if you’re taking other medications or have any underlying health disorders of the liver or kidneys.


  1. Clouatre, D. L. (2004). Kava kava: examining new reports of toxicity. Toxicology letters, 150(1), 85-96.
  2. Herberg, K. W. (1993). Effect of Kava-Special Extract WS 1490 combined with ethyl alcohol on safety-relevant performance parameters. Blutalkohol, 30(2), 96-105.
  3. Volz, H. P., & Kieser, M. (1997). Kava-kava extract WS 1490 versus placebo in anxiety disorders-a randomized placebo-controlled 25-week outpatient trial. Pharmacopsychiatry, 30(01), 1-5.