Forensic Implications of Kratom: Kratom Toxicity, Correlation with Mitragynine Concentrations, and Polypharmacy

Purpose of Review Kratom, a preparation of the leaves collected from the Southeast Asian plant Mitragyna speciosa , has increased in use within the United States (US) predominantly due to its stimulant and opioid-like effects. It contains many active alkaloids, most notably mitragynine. Clinical pharmacological research and toxicological information are limited, hindering forensic interpretation and an understanding of the role kratom use may play in death. Despite arguments from some vocal proponents and vendors that kratom poses no risk to users, there is a growing body of evidence that kratom use can result in significant adverse events, including death. Recent Findings Toxicological data for blood specimens analyzed between January 2018 and September 2022 in postmortem and driving under the influence of drugs cases were reviewed for the presence of mitragynine, the primary alkaloid of Mitragyna speciosa. Reported blood mitragynine concentrations, compound positivity, and concomitant findings were evaluated. Summary The forensic interpretation of mitragynine continues to be challenging. Kratom has been implicated in an increasing number of overdoses and deaths, and its significance is difficult to ascertain due to a substantial number of confounding variables, including a limited scope of toxicological testing and frequent co-positivity with drugs of abuse. Mitragynine has been listed as the primary toxicological finding in several overdose deaths albeit at a lower frequency compared to overall positivity, particularly when present at elevated concentrations (> 1000 ng/mL); these cases provide forensic confirmation of harms due to kratom use.