In 2015, Kirsten Smith was working in a Lexington, Kentucky, addiction treatment center as a part of her master's degree in social work when she had a life-changing conversation. A 27-year-old client, six months sober from the opioid OxyContin, told her he had begun using something called kratom to help with his anxiety, mood, and cravings.
Image credit: Will Kirk / Johns Hopkins University
"He said it made him feel good but not high," she remembers. "At the time I did not fully absorb the significance of what he said." Because kratom is marketed as an herbal supplement, Smith didn't believe the client was breaking the rules of his abstinence-only program. The program's administrators, however, citing kratom's psychoactive properties, discharged the client from treatment. Not long afterward, he died of a heroin overdose.
For Smith, who is today a Johns Hopkins assistant professor of psychiatry and behavioral sciences, it was a pivotal moment. Increasingly disillusioned with the "broken system" of addiction recovery—in which she says patients are stigmatized, stripped of autonomy, and often on the receiving end of non-evidence-based treatment—she decided to switch gears, trading the clinic for the lab.
"I didn't want to spend my life putting Band-Aids on gunshot wounds. I wanted to take the gun apart and figure out how it works," she says. "I wanted to be part of the larger process, the scientific inquiry that's attempting to better understand these things."
In the seven years since that conversation, Smith has become a leading voice in the contentious discussion over kratom. Derived from an evergreen tree native to Southeast Asia, kratom teas and capsules landed in U.S. smoke shops and gas stations around 2007, where they were marketed as an energy booster, mood enhancer, and pain reliever. Soon, people with opioid use disorder began hailing the supplement as a way to manage the brutal symptoms and intense cravings of opioid withdrawal syndrome. Skeptics, meanwhile, maligned kratom as "gas station heroin," as dangerous and addictive as the drugs it is purported to replace.
Working alongside "a little club" of scientists around the country, Smith has tried to bring evidence to bear on the debate, publishing some of the first scientific papers on kratom use in the U.S. during her postdoc at the National Institute on Drug Abuse. In 2024, she was the lead author on a first-of-its-kind study—funded in part by NIDA—that surveyed hundreds of kratom users about their habits, experiences, and motivations.
The work is deeply personal for Smith, who began injecting heroin in high school. "I did all of the drugs there were and was very addicted," she says. At the age of 23, after several failed attempts to quit, Smith and her then boyfriend robbed two banks to get money to buy more drugs. Eventually, Smith would serve four years in a federal prison, where she detoxed without medical care.
"When I came out the other side of that, I knew I wanted to be of service to others," she says. "Because of my past, I might be more interested in and more sympathetic to why people would want to take something to feel better, especially if they're not getting the care they need or want."
Anywhere from 2 million to 15 million people use kratom each year. While the substance does induce feelings of mild euphoria, Smith's work has found that the vast majority aren't using kratom to get high but rather for a whole host of other reasons.
Among them is relief for a range of afflictions, from chronic fatigue syndrome to irritable bowel syndrome, anxiety to ADHD. More than a quarter reported using kratom to replace opioids, and about 10% said it helped to blunt opioid withdrawal symptoms. "What we see are people rebuilding their lives, sometimes using kratom to deal with the cravings, pain, and fatigue of early recovery," Smith says.
Image credit: Will Kirk / Johns Hopkins University
That's because certain chemical components in kratom "act like opioids but are not opioids." The two most well studied are mitragynine and 7-hydroxymitragynine, alkaloids that activate the brain's mu opioid receptor, the same one stimulated by heroin and oxycodone. (Other alkaloids activate serotonin and dopamine receptors, much like a stimulant.)
Early research suggests that mitragynine and 7-hydroxymitragynine may not cause some of the more serious adverse effects associated with opioid use, but that it's still possible to develop physical dependence on kratom, "defined as tolerance or physical withdrawal symptoms," Smith says. "That's not up for debate at this point." According to one of her recent papers, 12.3% of users qualify as having substance use disorder for kratom, with symptoms that range from mild to moderate. However, preliminary FDA human studies of whole-leaf kratom, she says, "did not see indicators of abuse potential or severe adverse effects."
But Smith and her colleagues are "deeply concerned" about the recent proliferation of stronger, semisynthetic products derived from kratom, now flooding the market in the form of nasal sprays and liquid shots. These new products contain extreme levels of 7-hydroxymitragynine, with effects that are so powerful one researcher called them "legal morphine."
Currently, kratom is not regulated as a controlled substance, though the Drug Enforcement Administration lists it as a "drug of concern." Meanwhile, the FDA has not approved kratom for any purpose. In the absence of federal oversight, a growing number of states are enacting their own kratom regulations, restrictions, and bans.
Smith understands the desire to protect consumers but hopes cooler heads will prevail as scientists work to figure out how and in what form kratom can be safely consumed. "It's understandable to think that if you can get high from it, it must be bad," she says. "But do we want to have a moral panic freakout about it? Or do we want to approach it in a sensible manner?"
Noting that, "in real-world settings, kratom is already being used as a harm-reduction tool with seeming success," Smith is hopeful as scientists continue to study the chemical components of the substance, they'll eventually be able to develop research-backed treatments for the millions of people who are, as she once was, struggling to free themselves from the grips of addiction.
"There are a lot of people in America with complex health needs who are highly stigmatized, who are desperate to try something that will help them," she says. "I want to listen to what they have to say."
