Kratom might be the most popular herbal product you’ve never heard of.
Almost two million Americans used kratom in 2021, according to the Substance Abuse and Mental Health Services Administration’s National Survey on Drug Use and Health. Although it is banned in seven states kratom is ubiquitous at U.S. gas stations, convenience stores, and online.
Sourced from an Asian tree’s leaves, kratom produces weak opioid-like effects. It’s touted as an energy-boosting stimulant, a euphoric mood enhancer that can help anxiety or depression, and a treatment for chronic pain. But does it really work? Is it safe?
“It’s amazing how little information is out there given how many people use it,” says Peter Grinspoon, a physician at Massachusetts General Hospital and Harvard Medical School.
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Kratom leaves and teas have been used for centuries in Southeast Asia, but the products consumed in the United States are quite different and often far more potent.
The U.S. Food and Drug Administration lists kratom as a “drug of concern,” citing addiction and side effects like seizures, liver toxicity and, in rare cases, even death. Other adverse reactions to kratom use can include drowsiness, confusion, vomiting, or racing heartbeats. Yet because it’s not a food, dietary supplement, or drug, kratom has a nebulous regulatory status and can be sold in many places to those as young as 13.
Underlying this uncertainty is a lack of peer-reviewed research. “We really don’t have a scientific understanding of the safety or the efficacy of the product,” says Christopher McCurdy, a professor of medicinal chemistry at the University of Florida who has studied kratom use for over a decade.
What is kratom—and what does it do to the body?
The kratom tree (Mitragyna speciosa) is an evergreen in the coffee family, grown in Southeast Asia where fresh leaves are chewed as a mild stimulant, and teas are brewed as medicine to treat pain, diabetes, diarrhea, and other ailments including opium withdrawal.
In the U.S., kratom is sold in dried, powdered form that’s typically brewed in tea or taken in capsules. Gummies and liquid kratom doses are also sold, often with very high potency.
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Among kratom’s many chemically active compounds is mitragynine, which targets the same pain-reducing receptors that are stimulated by opioids like heroin, morphine, and fentanyl.
Another key compound is alkaloid 7-hydroxymitragynine, which has far more potent opioid-like impacts. Kratom plants contain very small amounts of 7-hydroxymitragynine but the amounts vary wildly in kratom supplements—some of which are adulterated with artificially high levels of this more addictive compound.
Kratom also binds to serotonin receptors, which regulate mood and anxiety, and it impacts dopamine release. These systems can also help reduce pain, McCurdy says—making it difficult to parse out which compounds are really at work. “We just don’t understand exactly how they are playing together,” he says.
Kratom is a stimulant at lower doses but, paradoxically, at higher doses it induces drowsiness or sedative reactions more akin to those produced by opiates.
Photograph by NurPhoto SRL
Does kratom really have health benefits?
McCurdy and colleagues’ surveys show the majority of kratom users believe it relieves their anxiety or chronic pain, and that they aren’t using kratom in an abusive way. “They say I take my two or three grams of powder, morning and evening, and it helps me function or gives me energy,” McCurdy says. “Of course we can’t say if it actually works because we don’t have the scientific studies to prove that.”
C. Michael White, a distinguished professor of pharmacy practice at the University of Connecticut, agrees. “Data on kratom use for anxiety, for alertness, to reduce fatigue, or any other purpose is very scant,” he says.
Though no randomized, controlled clinical trials have rigorously assessed pain relief in patients, some kratom research shows promise for short-term pain relief. However, some chronic kratom users do experience increased pain and sensitivity when they stop taking it.
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“I would never suggest someone use kratom as a pain reliever because the benefits are not established, there are many other options, and there are real risks,” White says.
Kratom use is common among those with opioid use disorder. Although no randomized, controlled trials prove its merit for addiction treatment, White says many people argue that using kratom helps keep them from more dangerous illicit opioids.
“This is where kratom may actually have a role in our healthcare system,” White says. “If you have access to addiction treatment, definitely try the proven options first. However, if you are unable to afford treatment, you are unwilling to out yourself and admit you have addiction, or you are not being provided sufficient treatment and will relapse to illicit opioid use, kratom is likely a much better option.”
“Kratom seems much less likely to stop someone from breathing than other opioids,” he adds, “because it is a central nervous system stimulant not a depressant.”
Is kratom safe?
While kratom teas and other fresh leaf products have long been used safely in Southeast Asia, studies have shown Western users often consume very different stuff—with huge, unknown variations in the amount of active chemical ingredients.
“There’s a variety of products that are called kratom, but I compare it to the range from a Miller Light to Everclear,” McCurdy says. “We know there is a spectrum from safe to toxic, but we don’t know where the break point is.”
Dried leaf material sold in capsules or bulk powder, used to make teas or just consumed whole, tends to be less potent, McCurdy notes. Other kratom supplements are made from leaves that have been processed, refined, or manipulated to produce extract products that deliver a higher chemical dose with a higher risk of negative effects.
Then, at the extreme end, there are kratom supplements that McCurdy says are essentially synthetic 7-hydroxymitragynine products. “Some things being marketed as kratom are so far removed from the plant that they are basically pharmaceuticals,” McCurdy cautions. These can more easily be over-consumed, sometimes with serious consequences, sometimes by people who hope it will give them a euphoric high. “Unfortunately it doesn’t work like that,” he says. “All of a sudden you have a huge amount of exposure into your system and could be suddenly in the ER experiencing very negative side effects.”
Some kratom products aren’t labeled either, so buyers may not be able to tell how potent they are—and since kratom isn’t regulated or tested it can be adulterated with lead and other heavy metals, or even other chemicals, the FDA warns.
“It’s the Wild West, in my opinion, and it’s buyer beware,” McCurdy says.
Is kratom addictive?
Compared to strong opioids like morphine, heroin, and oxycodone, the risk of becoming addicted to kratom is relatively low; however the FDA warns that people can become addicted after taking it for long periods of time for pain, anxiety, or to boost mood or energy.
“You start out voluntarily taking it, but at a certain point you need to take it just to feel regular,” White says. “Then if you don’t take it instead of going back to your normal state you feel worse.”
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Some research, including a recently completed FDA Single Ascending Dose trial, suggests that taking kratom in reasonable doses may do little harm in the short term, says McCurdy, whose team partnered on the research. But the research included only a single dose, and the possible consequences of long-term use aren’t well known.
Numerous states have pending legislation to limit concentrations of mitragynine or 7-hydroxymitragynine in kratom products, impose age restrictions on who can buy them, and require products to be labeled and tested.
That seems like a sensible step to Grinspoon. “In a perfect world there would be a safe, regulated supply, because I actually think it can be helpful to people,” he says.
“But I also think that kratom shows some of the big gaps in a regulatory landscape that put a lot of people at risk,” he adds. “A lot of people that take this are young people—and right now it’s sort of like an uncontrolled experiment.”