Mitragynine is the main active alkaloid constituent of the plant Mitragyna speciosa Korth. Mitragyna speciosa Korth. (M. speciosa), from the Rubiaceae family, is a tropical medicinal plant native to Southeast Asia. In Malaysia, M. speciosa leaves are known as Ketum or Biak, and in Thailand as Kratom. M. speciosa has been historically used in Southeast Asia as a stimulant drug and in its traditional context as a remedy for various symptoms. Pharmacological activities are mainly mediated via opioid receptors as well as neuronal Ca2+ channels, expression of cAMP and CREB protein and via descending monoaminergic system. Mitragynine acted as a partial agonist at mu-opioid receptors, in contrast, at kappa-opioid receptors, mitragynine was a competitive antagonist, similarly, mitragynine acted as an antagonist at delta-mu-opioid receptors, but with very low potency. Experimental studies in animals have now shown that mitragynine has an addictive potential, however, only at higher doses. Human users in countries of frequent use with a traditional context report a rather low daily consumption with only mild side effects. Kratom and mitragynine can be instrumentalized to enhance physical work power and endurance. A major reason for Kratom consumption is its reported efficacy to replace opiates in chronic users. This makes the Kratom plant preparation and also the isolated compound mitragynine interesting options to treat opiate addiction. In August 2016, the US Drug Enforcement Administration announced plans to classify kratom and its mitragynine constituents as Schedule 1 controlled substances.