Mitragyna speciosa (commonly known as kratom[3]) is a tropical evergreen tree in the coffee family native to Southeast Asia. It is indigenous to ThailandIndonesiaMalaysiaMyanmar, and Papua New Guinea,[4] where it has been used in herbal medicine since at least the nineteenth century.[5] Kratom has opioid properties and some stimulant-like effects.[6][7]

As of 2018, the efficacy and safety of kratom are unclear, and the drug was unapproved as a therapeutic agent due to the poor quality of the research.[8][9] In 2019, the United States Food and Drug Administration (FDA) stated that there is no evidence that kratom is safe or effective for treating any condition.[10] Some people take it for managing chronic pain, for treating opioid withdrawal symptoms, or for recreational purposes.[4][8] The onset of effects typically begins within five to ten minutes and lasts for two to five hours.[4]

Anecdotal reports describe increased alertness, physical energy, talkativeness, sociability, sedation, changes in mood, and pain relief following kratom use at various doses.[8] Common side effects include appetite loss, erectile dysfunctionnausea and constipation.[11] More severe side effects may include respiratory depression (decreased breathing), seizureaddiction, and psychosis.[4][6][12][13] Other side effects may include high heart rate and blood pressure, trouble sleeping, and, rarely, liver toxicity.[4][14][15][16] When use is stopped, withdrawal symptoms may occur.[8][7] Deaths have occurred with kratom both by itself and mixed with other substances.[6][17] Serious toxicity is relatively rare and generally appears at high doses or when kratom is used with other substances.[4][8]

Kratom is a controlled substance in 16 countries[6] and, in 2014, the FDA banned importing and manufacturing of kratom as a dietary supplement.[18] As of 2018, there is growing international concern about a possible threat to public health from kratom use.[6][8][19] In some jurisdictions, its sale and importation have been restricted, and several public health authorities have raised alerts.[8][19][20]