Systematic Review: 55 Cases Show Kratom-Associated Deaths Often Involve Polypharmacy; Pure Kratom's Role Remains Unclear

Why it matters

This systematic review challenges assumptions about kratom's lethality by revealing that 42% of 95 reviewed cases involved confounding substances that could have caused or contributed to deaths. The findings suggest the scientific literature may overattribute deaths to kratom when polypharmacy plays a significant role, shifting the discussion toward understanding interaction risks rather than kratom toxicity alone.

The big picture

Researchers analyzed 95 human case reports of acute adverse effects from kratom use, including 35 deaths. Mitragynine was toxicologically confirmed in 55 cases. Fatal cases showed mitragynine levels of 3.5–7,500 ng/mL; living cases, 5–340 ng/mL. Critically, 32 of 39 deceased cases involved other confounding substances, yet many publications attributed deaths solely to kratom. The review found widespread inadequate toxicology testing and incomplete medical histories, limiting causal conclusions.

Key findings

• 95 case reports reviewed; 35 deaths, 20 survivors with mitragynine confirmation. Reported adverse effects: pulmonary, cardiovascular, neurological, hepatic, renal, gastrointestinal, seizures, and altered mental state. 42% of deaths (32/76 total cases) involved confounding substances possibly responsible. Wide mitragynine level variation suggests dose-response uncertainty. Literature shows weak toxicology methodology. Kratom alone may not increase risk of severe adverse effects.

What they say

The authors conclude: 'Currently, the literature provides insufficient evidence to support the claim that kratom consumption alone increases the risk of severe acute adverse health effects. More research is necessary to isolate the effects of kratom from those of polypharmacy.'

Bottom line

A systematic review of 95 kratom cases found that the majority of deaths involved other drugs, suggesting kratom's independent toxicity may be overestimated in medical literature due to inadequate testing and case documentation.