Kratom, formally called Mitragyna speciosa, is a type of tree native to Southeast Asia related to the coffee plant. For centuries, those native to Southeast Asia have chewed on kratom leaves or made a tea from kratom as a stimulant for pain relief. It’s also used in that part of the world to cope with heroin withdrawals.
As an herbal supplement, kratom is available in the U.S., typically found in smoke shops or online. Instead of the fresh leaf form, it’s usually made with powdered dry leaves sold as tablets or capsules, although sometimes used as a tea. When it goes from fresh leaves to the powdered form, its chemistry and effects may change, says Christopher McCurdy, a medicinal chemist and behavioral pharmacologist who has done extensive kratom research at the University of Florida in Gainesville. McCurdy is a professor and The Frank A. Duckworth Eminent Scholar Chair at UF.