Mitragyna speciosa (commonly known as kratom s a tropical evergreen tree in the coffee family native to Southeast Asia. It is indigenous to Thailand, Indonesia, Malaysia, Myanmar, and Papua New Guinea, where it has been used in herbal medicine since at least the nineteenth century. Kratom has opioid properties and some stimulant like effects.

Anecdotal reports describe increased alertness, physical energy, talkativeness, sociability, sedation, changes in mood, and pain relief following kratom use at various doses. Common side effects include appetite loss, erectile dysfunction, nausea and constipation. More severe side effects may include respiratory depression (decreased breathing), seizure, addiction, and psychosis.

Other side effects may include high heart rate and blood pressure, trouble sleeping, and, rarely, liver toxicity. When use is stopped, withdrawal symptoms may occur. Deaths have occurred with kratom both by itself and mixed with other substances. Serious toxicity is relatively rare and generally appears at high doses or when kratom is used with other substances.