However, other studies also have shown that users can experience withdrawal symptoms, Eggleston said.
“That suggests that patients could develop a dependence or a substance use disorder, as you would with other opioids,” Eggleston said. “To me, that exceeds what I would consider a reasonable risk for an herbal supplement you can buy at a local convenience store or head shop.”
Kratom proponents argue that the new study is flawed because it relies on poison control and medical examiner data, which tags kratom as the main suspect and could fail to consider other possible explanations.
“If a person dies and the tox screen identifies kratom in the bloodstream, that is labeled as a kratom-associated death,” said Mac Haddow, a senior fellow on public policy at the American Kratom Association. “It is just as plausible you could identify caffeine in the bloodstream as a result of drinking a cup of coffee that morning.”
Susruta Majumdar, an associate professor with the St. Louis College of Pharmacy in Missouri, said the new study adds a bit more evidence regarding kratom’s safety, but agreed that its reliance on poison control center data makes for a flawed approach.
Based on available data, Majumdar said, kratom probably is safer that prescription and illicit opioids, but “I think we are getting to a point where we can say it’s addictive.”
Majumdar added that he believes kratom-related deaths are not caused by kratom alone, but kratom combined with other substances.
“People are on multiple drugs, and it’s the synergy between those drugs that is causing the toxicity,” Majumdar said.
Eggleston said he does not advocate a ban on kratom, since studies suggest it might have a role in treating chronic pain and addiction.
Instead, clinical trials are needed to assess kratom’s usefulness and establish its safety at certain doses, Eggleston said.
“Our research is not coming from a place where we want to hinder access,” Eggleston said. “We want the public to have all the information they need and be transparent, so they know what works and what’s safe.”
The study findings were published July 9 in the journal Pharmacotherapy.