This article was updated on March 1 with additional information on kava side effects.

This is a follow-up to my post last week, describing my visit to a shop purveying beverages laced with kava and with kratom, two substances I had not heard of previously. As a service to readers who may deal with someone who is using these materials, here is what I have found out about what they do to people.

Upfront disclaimer: I have no expertise in this area, these are just the observations of an amateur who has read a few articles. Do not make any decisions based on this article.

Primary Effects of Kava

Kava is made from the roots of a plant in the pepper family, which is native to the Pacific Islands. There are two main classes of kava plants. The “noble” cultivars are what has traditionally been used for human consumption, via water extraction of the roots to make a beverage. The non-noble (two-day or “tudei”) cultivars grow faster (so they are cheaper for production), but are more likely to have adverse side effects. Also, the above-ground parts of the plants are known to contain toxic alkaloids.

The Wikipedia summary of effects is, “Systematic reviews and meta-analyses conducted in the last decade have typically indicated a modest positive effect of kava on anxiety and generalized anxiety disorder, though the evidence is mixed and further research is frequently recommended.”

I found a 2020 memo by a FDA toxicologist, titled “Review of the published literature pertaining to the safety of Kava for use in conventional foods”, which covers both the positive effects and the extensive side-effects. The memo notes: “The major physiological action in humans is consistently reported as a pleasant, mild, centrally acting relaxant property which induces a generalized muscle relaxation and, ultimately, a deep natural sleep. A minor property of kava is its local anesthetic properties which are experienced as numbing of the mucous membranes of the mouth and tongue when the beverage is consumed.” That all sounds pretty nice.

The main active compounds in cava are called kavalactones. Known effects of the six major kavalactones are:

Source: FDA 2020

For the biochemists among us: “The psychotropic effects of kava are achieved by the modulation of gamma‐amino‐butyric acid (GABA) receptors. Although the exact mechanisms are not known, studies suggest that the effects are mediated via different mechanisms such as upregulation of GABA‐A receptor function, blockade of voltage‐gated sodium ion channels, enhanced ligand binding across GABA‐A receptor subtypes, and reduced excitatory neurotransmitter release.”   GABA is the primary inhibitory neurotransmitter in the central nervous system, so it is commonly targeted by tranquilizers such as benzodiazepines (e.g. Valium). Hence, the calming effect. Research suggests that kava components also inhibit the re-uptake of norepinephrine (a chemical that makes you feel alert) and of dopamine (a feel-good hormone).

Side Effects of Kava

The most controversial issue is liver damage. There were a number of very severe cases (complete liver failure) in the late 1990s/early 2000s in Europe, which led to a ban of kava in a number of countries there starting around 2002. It was not banned in the U.S., but the FDA issued an advisory letter expressing concern about liver damage.

Kava advocates were unconvinced, and further research seems to indicate that nearly all of those liver damage cases were due to use of the non-noble cultivars and/or the use of stems instead of just the roots and/or the extraction being done with some alcoholic solvent rather than water (probably due to greedy/ignorant kava suppliers). Most European countries have relaxed their outright bans, although in many cases kava sales are still restricted or regulated. Because their main market got shut off due to the liver problems, Pacific island nations scrambled to rebuild kava credibility. They now try to ensure that only proper kava is exported to the West.

Kava advocates claim that if kava is extracted the traditional way from traditional cultivars, there are no appreciable severe bad side-effects. On the other hand, the 2020 FDA memo document claimed there was a wide range of serious adverse effects of kava use among traditional kava users in the eastern Pacific, especially liver damage, among heavy kava drinkers: “Several studies show a clear association of increased level of liver enzymes GGT, ALP, and moderate to heavy kava beverage consumption as shown in Table 2…..Hepatic injury due to traditional aqueous extracts of kava root was reported in a study of 27 heavy kava drinkers in New Caledonia (Russmann et al. 2003).”

On closer examination, however, it seems that the FDA document gave an overly negative view of kava liver effects. The Russman 2003 study did not actually show “heptatic injury” among the 27 heavy kava drinkers. All it showed was elevated levels of the liver-related enzymes. It is true that there were pretty consistent observations of elevated levels of enzymes such as GGT (gamma-glutamyl
transpeptidase) and ALP (alanine aminotransferase) in blood samples. Most of the studies of Polynesian subjects cited in the FDA memo lacked controls, but Brown (2007) included kava users and nonusers in its survey of Tongans living in Hawaii. This study showed high levels of GGT and ALP among the kava users, yet without any clinical indications of liver malfunction. Also, other liver-related markers in the blood such as AST, ALT, bilirubin, and ferritin were normal in the kava users. The significance of the partial abnormalities in enzymes is not clear. My guess is that the liver is somewhat stressed but not to the point of malfunction.

So it seems true that moderate consumption of kava prepared the traditional way (water extraction from roots of noble cultivars) shows no general tendency for observable liver damage. That said, the elevated liver-related enzymes are grounds for at least a little caution, and there have been a (very) few cases of genuine liver damage from traditionally extracted kava. Russman (2003) reported two women in New Caledonia who developed symptoms of liver distress from kava; these symptoms resolved after cessation of kava use. And Becker (2019) documented the case of an otherwise healthy woman in Brazil who experienced complete liver failure following 52 days of using an approved kava pill at approved dosage; her life was saved by a liver transplant. However, people die every year from eating peanuts, so I don’t know how much to read into these isolated cases of liver damage from kava.

A common effect of kava use is dermatitis, presenting as dry skin, rashes, and eruptions. (This strikes me as an allergic-type reaction). Other common side-effects can be nausea and headaches. These effects typically resolve quickly if kava use is discontinued. In the plus column, there is some sketchy evidence for anti-cancer activity by kava. In general, cognition is not impaired.

I read about sixty reviews on Amazon from purchasers of kava root powders, and more discussions on Reddit. Most were quite happy with the kava products, but emphasized that preparing the drink from the root takes some time and effort to squeeze and then filter; the brew tastes terrible, like dirt (you have to gulp it down, not sip it), and some temporary nausea is common. However, there were a nontrivial minority that reported very ugly experiences, and one man who with his first dose went comatose and nearly died. The general opinion is that kava beverage made fresh (by you or at a kava bar) from the ground root is better than capsules or packaged drinks made from kava extracts.

The exact effects may depend on your genome – some folks may get whacked, while others escape unscathed. And there may be systemic differences between how Caucasians and Polynesians react to kava. Apparently you must chug it down on an empty stomach to get the full effects. It is best to drink it in multiple small increments, rather than one giant glass. Some users chase each “shell” with a swish of some other beverage to clear the taste out, and/or eat a tiny snack like a few chips to calm the queasy stomach.

Side effects seem to be greatly amplified when kava is consumed with other substances, especially alcohol. That makes chemical sense, since kava acts on many of the same metabolic pathways as alcohol and antianxiety meds like benzodiazepines and barbiturates. This is significant, since in the West kava is often consumed in a social context which includes alcohol.

For further reading on kava effects: see an objective 2022 review by Soarez, and many pro-kava articles such as this on the kava promotion site kavacoalition.org. That site includes testimonials of people using kava instead of opioids for coping with chronic pain from injuries. Although its main function is to reduce anxiety, that in turn may mitigate the sensations of pain. A number of participants in a Reddit thread stated that kava has helped them overcome alcoholism.

One source estimated that there are about 200 kava bars in the U.S., with about half of them in Florida. After a court battle with the state, a kava bar opened in Virginia in 2024. The state has so far has not approved serving of kratom.

My takeaway on kava: It seems to me to be somewhat similar to cannabis or alcohol – light, occasional use can give a good feeling, especially pleasant as a shared experience with friends. For some, it might be helpful in coping with pain. Unlike alcohol, there seems to be no obvious tendency towards addiction. However, as with alcohol and cannabis, there is some possibility of serious adverse effects, especially with heavy use and if it is consumed with other substances.   Therefore, it would seem wise to start slow with kava and monitor your body’s reactions.

Also, it is essential to make sure you are getting kava made the right way, as discussed above. At a kava bar, you can talk with the server. If you are taking capsules, I’d suggest contacting the manufacturer. Or you can buy plain kava root, and steep your own brew.

Effects of Kratom

I will spend less time on kratom effects, since it acts largely like an opioid. Need we say more.

Kratom is extracted from the leaves of an evergreen plant native to southeast Asia. We discussed some of the varieties of kratom earlier.  Quotations here are all from the Wikipedia article; they mesh with what I have read elsewhere.

The active compounds are a mix of dozens of alkaloid compounds. The key ones seem to interact with opioid receptors in the brain. But the interactions are complex and poorly-understood. On the plus side, “These compounds display functional selectivity and do not activate the β-arrestin pathway partly responsible for the respiratory depression, constipation, and sedation associated with traditional opioids.”

For recreational use, “At low doses, kratom produces euphoric effects comparable to those of coca. At higher doses, kratom produces opioid-like effects.”   Much of kratom use is for more serious issues, such as managing chronic pain or helping with opioid withdrawal.

There are many documented adverse side effects, resulting in many visits to hospitals:

Common side-effects include appetite loss, erectile dysfunction, nausea and constipation. More severe side-effects may include respiratory depression (decreased breathing), seizure, psychosis, elevated heart rate and blood pressure, trouble sleeping, and, rarely, liver toxicity. Addiction is a possible risk with regular use: when use is stopped, withdrawal symptoms may occur. A number of deaths have been attributed to the use of kratom, both by itself and mixed with other substances.

…Long-term use of high doses of kratom may lead to development of tolerance, dependence, and withdrawal symptoms, including loss of appetite, weight loss, decreased libido, insomnia, muscle spasms, muscle and bone pain, increased yawning and/or sneezing, myoclonus, watery eyes, hot flashes, fever, diarrhea, restlessness, anger, and sadness. This may lead to resumption of use. Frequent use of high doses of kratom may cause tremors, anorexia, weight loss, seizures, psychosis and other mental health conditions.

Perhaps the biggest concern with kratom is the high propensity for addiction and the need to increase dosage to obtain the desired effects:

Kratom is a botanical with a known addiction liability and, in vulnerable individuals, dependence may develop rather quickly with tolerance noted at three months and four- to ten-fold dose escalations required within the first few weeks…Kratom addiction carries a relapse risk as high as 78% to 89% at three months post-cessation.

In 2017 the FDA stated that “There is no reliable evidence to support the use of kratom as a treatment for opioid use disorder; there are currently no FDA-approved therapeutic uses of kratom… and the FDA has evidence to show that there are significant safety issues associated with its use.”

Some advice here on Reddit on how with kratom “less is more” — due to complex biochemical interactions, upping your dose or making it more frequent can actually diminish the desired effects, and start down the road of diminishing returns and then using higher and higher doses. And this Reddit where users describe their problems with kratom addiction:

i suggest you stop while you are still able to walk away relatively unscathed. addiction is a very disgusting thing that can happen to a person. you will absolutely feel worse than you ever thought you could feel, save for losing a child or something insane happening IRL.

some drugs will actually cause a physical addiction, like kratom. this means your body adjusts to it & stops doing its job in order to let the drug do it. now when you stop using, your body & mind are without their own processes & they are also without the drug. this leaves you empty, sick, wide awake but exhausted, sweaty but cold, aching pain. for alcohol, withdrawal can actually lead to seizures, extreme hallucinations & delusions, & even will just straight up kill you bc you need a drink so bad.

My takeaway on kratom: This one seems like playing with fire, due to its addictive properties. Also, street doses of kratom are sometimes spiked with horrible drugs like fentanyl. Thus, I see little case for promoting it for recreational use, given that there are safer alternatives such as weed, booze, and kava. (And in general, there are more fruitful ways to rise above anxiety than drinking or smoking something – – change your thinking patterns, or even use flashing lights to put your brain into alpha waves. )

It is possible that kratom could be useful to someone dealing with chronic pain, as an alternative to opioids with their known addition danger. I have deep sympathy for anyone in that position. I would hope that they would work with a medical professional or at least a trustworthy friend to monitor their usage (keeping it low, no matter what), since in these matters it is easy to deceive oneself as to what is really going on.

ADDENDUM

In case someone is tempted to try kratom out of curiosity, I will share the cautionary observation an acquaintance emailed me after reading the original version of this article:

You know, I met some heroin addicts who said that they always told themselves they wouldn’t do it, they had seen it destroy people. But they ended up one day just caving to curiosity. One day, they just shrugged and said “screw it, I wanna see what this is about.” And their life was ruined by the immediate addiction. It’s a very sad story.