Mitragynine is the predominant alkaloid produced by the southeastern Asian plant Mitragyna speciosa Korth., a member of the coffee family (Rubiaceae). It was isolated in 1921 by Ellen Field, a medicinal chemist at the University of Edinburgh.

M. speciosa, known locally as kratom, has been used in traditional medicine for ≈200 years. It has opiate-like properties and has been used to treat chronic pain and opioid withdrawal symptoms. More recently, it has come into recreational use. Clinical studies on kratom and mitragynine are just beginning.

In September 2016, the US Drug Enforcement Administration (DEA) designated kratom, mitragynine, and one of its derivatives as Schedule I substances. Schedule 1 is the most restrictive category under the US Controlled Substances Act. DEA cited the lack of information on mitragynine and reports of adverse reactions—even death—from taking kratom.

Researchers studying the medical use of mitragynine and its pseudoindoxyl derivative decried the Schedule I classification. One of them, Andrew C. Kruegel at Columbia University, said, “Placing these compounds into Schedule I will erect an enormous barrier to scientific research in this field and will dramatically curtail our work with this exciting plant.”