7-Hydroxymitragynine is a terpenoid indole alkaloid from the plant Mitragyna speciosa, commonly known as Kratom. In mice, it is orally active and has analgesic effects. 7-Hydroxymitragynine is a partial agonist at the μ-opioid receptor with a potency, calculated using pD (2) values, that is 30-fold higher than that of mitragynine and 17-fold higher than that of morphine, respectively. As a G protein biased ligand at this receptor it causes significantly less side effects than morphine, like constipation, development of tolerance and withdrawal syndrome upon abstinence. The O-acetyl ester (Acetoxy), 7-acetoxymitragynine has also been reported and found to be an active μ-opioid agonist.