Kratom Side Effects: Risks to Know

Kratom, a plant-based supplement, has been used in Southeast Asia for thousands of years as a way to enhance focus and relieve pain. But tales of kratom side effects may make you nervous or unwilling to start or continue taking kratom.

“Some users report [kratom] helps them manage chronic pain, anxiety, and opioid withdrawal symptoms,” says Richard J. Hamilton, MD, a professor and the academic chair of the emergency medicine department at Drexel University College of Medicine in Philadelphia. “However, due to insufficient research, lack of standardization, and concerns over safety, kratom is not officially recognized in modern medicine.”

Kratom advocates point to its stimulant and narcotic effects as reasons to use it. But some of the side effects of kratom — both short- and long-term — can be serious. One kratom health risk is its potential to interact with a large number of prescription and over-the-counter drugs, as well as potentially harmful or addictive recreational drugs. Some of these interactions may be fatal.

So what negative effects of kratom do you need to be aware of? At what dosages? And how long until you experience them? Let’s break down the answers to these questions and more.

The kratom in supplements derives from a tree, Mitragyna speciosa, that’s native to southeast Asia. You can find it for sale online and in some smoking shops. Most kratom products are ground or loose dried leaves, often in capsules. Recently, however, there has been an explosion of potent concentrates, tinctures, gummies, and more.

The kratom plant is a member of the coffee family (Rubiaceae), and causes caffeine-like effects like increased focus and alertness. Kratom’s main active compound, an alkaloid called mitragynine, is chemically similar to — but not identical to — opioids, so kratom can also have calming and pain-relieving effects as well.

“At lower doses, mitragynine may stimulate the release of neurotransmitters like dopamine and norepinephrine, leading to increased energy and alertness,” says Dr. Hamilton. “At higher doses, the opioid-like effects dominate, producing sedation and analgesia [pain relief unaccompanied by loss of sensation or alertness].”

What Is Mitragynine?

“Mitragynine and some of the other alkaloids in kratom are what we call a partial opioid agonist,” says Oliver Grundmann, PhD, a professor and researcher at the University of Florida’s College of Pharmacy and the 2022–24 president of the American College of Clinical Pharmacology.

Dr. Grundmann explains that true opioids attach themselves to sites called opioid receptors on cells in your central nervous system (called neurons). Mitragynine does the same, but only partially.

“The effects of a partial agonist like mitragynine will top out at a certain amount,” says Grundmann. “And when you go past that amount, you don’t get more activation of more opioid receptors, whereas with an opioid like heroin, morphine or fentanyl, you would get that [increased opioid receptor activation].”

Notably, that means that kratom doesn’t cause breathing to slow or stop in the way that too high a dose of opioids can. “However, this doesn’t mean kratom is without risks, especially at high doses or in combination with other substances,” says Hamilton.

Mitragynine also binds to other receptors besides opioid receptors, such as receptors for the neurotransmitter serotonin and those for adrenal hormones like epinephrine, causing kratom’s stimulating effects.

• Agitation
• Nausea
• Itching
• Sweating
• Dry mouth
• Constipation
• Diarrhea
• Increased urination
• Loss of appetite
• Drowsiness
• Tachycardia, an abnormally fast heartbeat (feeling like your heart is racing or fluttering)
• Loss of muscle coordination in the arms or legs
• Hallucinations
• Seizures
• Liver damage

Dose and Delivery

Kratom’s effects — intended and otherwise — are generally dose-dependent, meaning the more you take the more you’ll feel. “There is no universally accepted safe dosage range for kratom, due to its variable potency and individual responses,” says Hamilton. “However, anecdotal evidence suggests that a low dose of 1 to 5 grams (g) may provide mild stimulant effects, while higher doses of around 5 to 15 g might yield sedative effects.

Grundmann says taking kratom leaves in capsule or tea form is self-limiting “because you can only ingest so much before nausea, and potentially vomiting, sets in,” he says. “Your stomach will tell you eventually that, ‘No, this is not sitting well with me.’”

This is also why new, more concentrated formats and delivery methods of kratom worry Grundmann. “Traditional, ground-leaf kratom products have about 2 percent to 4 percent of mitragynine and 6 percent to 7 percent total alkaloids,” he explains.

“But now we see concentrates that contain 40 or 50 percent mitragynine,” he says. “You’re getting multiple times what you would get with the native kratom leaf material in a very small amount of volume, making it easier to overdo it and make yourself sick,” he says.

According to Hamilton, long-term side effects may include:

• Dependence and withdrawal symptoms upon cessation
• Liver damage or hepatotoxicity
• Weight loss
• Sleep disturbances
• Potential mental health issues, such as depression or anxiety

“These effects may start to become apparent after several weeks of consistent use,” says Hamilton.

The good news, says Grundmann, is that these long-term effects seem reversible. “People experiencing insomnia who stop taking kratom at night will probably sleep better," he says.

Likewise, if someone with elevated liver enzymes — which usually signal injury to the liver — “stop[s] taking kratom, liver function tests go back to normal,” says Grundmann. “There don’t seem to be long-term effects that last beyond the intake of kratom.”

Is Kratom Addictive?

• Muscle pain, cramps, and body aches
• Shakiness or tremors
• Nausea or vomiting
• Abdominal pain
• Diarrhea
• Sweatiness or hot flashes
• Fever
• Difficulty sleeping
• Nervousness
• Restlessness
• Sadness or depressed mood
• Anger

Contact your healthcare provider immediately if you experience any adverse side effects after using kratom or if you’re having trouble stopping kratom use.

“Better regulation could allow for more quality control, standardization, and labeling requirements,” says Dr. Hamilton. “That may cut down on some kratom side effects. But, mitragynine and the other compounds in kratom have the potential to cause side effects regardless of quality control issues.”

Kratom may pose health risks apart from overdose.

Drug Interactions

Drug interactions are one of the greatest risks for those taking kratom. “There are many, many potential drug interactions, especially with drugs for behavioral health and drugs that act in the central nervous system or are metabolized by the liver,” says Hamilton. “Some of them may potentially be fatal.”

“Mitragynine prevents that metabolism as well,” says Grundmann. “They inhibit that enzyme and you get higher concentrations of certain drugs in the bloodstream that can lead to toxic effects.” Mitragynine may also slow the formation of other metabolizing enzymes, as can other alkaloids found in kratom.

Contamination

“For anyone who wants to engage with kratom, definitely make sure you’re choosing products that have labels on them that actually tell you what’s in it,” says Dr. Grundmann. He also recommends talking to your healthcare provider if you take medication for a chronic condition, to make sure kratom is safe.

“I know many people do it and dietary supplements are used by loads of people, but I would advise against self-treating,” says Grundmann. “If someone really wants to take kratom, start with low doses. Once they feel they get some benefit, stop at that dose and don’t take more. If they feel like they have developed a tolerance, or if they develop withdrawal symptoms, then it’s time to talk to a healthcare professional.”

• Kratom’s short-term side effects can include agitation, tachycardia, nausea and vomiting, drowsiness, and confusion.
• Kratom’s long-term side effects can include liver damage and insomnia, and it can cause withdrawal symptoms when you stop taking it.
• Kratom can interact dangerously with a wide variety of drugs, so get the all-clear from your healthcare provider before you take it.