Kratom is a species of tree (Mitragynia speciosa) that grows in Southeast Asia and Africa. In low doses, kratom leaves act as a stimulant. In high doses, it has analgesic effects. It is not a classic psychedelic and it is unclear how much, if any, the serotonin 5-HT2a receptor is involved in the effects of kratom compounds. It is likely that the combination of effects from several different types of receptors is responsible for benefits from the compound, which include relief from symptoms of opium withdrawal, anxiety and depression. More than a dozen countries have made kratom a controlled substance, limiting the sale, use, importation, and production of kratom. Neither the UN nor the US has currently scheduled kratom, the latter is considering scheduling it as of July 2021. The FDA did ban the importation of kratom in 2014; until then it was promoted as a dietary supplement.