7-Hydroxymitragynine (7-OH-MIT, often simply referred to as7-OH) is aterpenoidindolealkaloid present in the plantMitragyna speciosa (the leaves of which are commonly known askratom).[3] It was first described in 1994.[4] In humans, it is produced as an active metabolite ofmitragynine via hepatic oxidation.[5] 7-OH exhibits greater binding affinity toμ-opioid receptors (MOR) than mitragynine.[citation needed]
7-OH-MIT, like mitragynine, appears to be a mixed opioid receptoragonist/antagonist, with recent research indicating that it acts as apartial agonist atμ-opioid receptors and as a competitive antagonist atδ- andκ-opioid receptors.[6][7] Both 7-OH-MIT and mitragynine do not appear to activate theβ-arrestin pathway, distinguishing it from traditionalopiate andopioid chemicals.[6]A study has found the binding affinity of 7-OH-MIT to beμ-opioid receptor (MOR) 37 (± 4) nM andδ-opioid receptor (DOR) 91 (± 8) nM andκ-opioid receptor (KOR) 132 (± 7) nM.[8]Another study found the binding affinity of 7-OH-MIT to be MOR 16 (± 1) nM and DOR 137 (± 21) nM and KOR 133 (± 37) nM.[9]Another study found the binding affinity of 7-OH-MIT to be MOR 13.5 nM, DOR 155 nM, and KOR 123 nM.[9] Cross-tolerance to morphine was evident in mice rendered tolerant to 7-hydroxymitragynine and vice versa.Naloxone-induced withdrawal signs were elicited equally in mice chronically treated with 7-hydroxymitragynine ormorphine.[10]
In natural kratom leaves, 7-hydroxymitragynine is only present in small amounts, comprising less than 2% of overall alkaloid content.[11] Therefore, extracting 7-OH-MIT in high concentrations directly from natural kratom leaves is not practical. Instead, 7-hydroxymitragynine can be producedsemisynthetically via the oxidation of mitragynine.[5]
7-OH has been rising in popularity as arecreational drug, particularly in theUnited States. Its ability to bind to opioid receptors can cause addictive effects. In an electrical stimulation test using guinea-pig ileum, 7-OH performed 13 times greater pain relief than that of morphine.[12] The drug's novelty has meant that it has increasingly been sold unregulated over the counter in gas stations and smoke shops, often in highly concentrated "candy-like" or pill form alongsidekratom powder and other supplements with little to no information provided to consumers about its effects.[11]
According to the United States Poison Control Center, the number of cases relating to kratom-based products such as 7-OH have increased from under 200 in 2014 to 1600 in 2024, with approximately 40% of 7-OH reports coming from individuals who were abusing the drug.[13]
In July 2025, theFood and Drug Administration (FDA) formally recommended that theDrug Enforcement Administration (DEA) classify 7-hydroxymitragynine as acontrolled substance.[14] This action is not directed towardMitragyna speciosa itself, which will remain unaffected by regulation of 7-OH.[15] Despite claims by marketers for products that contain 7-OH that they can be used to treatanxiety and pain, the drug is not approved by the FDA for any medical use or as a food supplement.[16]
On August 13, 2025, Florida attorney generalJames Uthmeier announced an emergency rule placing 7-hydroxymitragynine into schedule I status under Florida state law, effectively outlawing the substance and removing it from all headshops and similar stores from the state.[17][18][19]
Studies on 7-hydroxymitragynine's safety have been unable to identify anLD50 orally with no deaths occurring.[20] 7-hydroxymitragynine has been described as a "prototypical" compound to develop a new generation of opioids with an improved safety profile.[21]
^Matsumoto K, Horie S, Ishikawa H, Takayama H, Aimi N, Ponglux D, et al. (March 2004). "Antinociceptive effect of 7-hydroxymitragynine in mice: Discovery of an orally active atypical opioid analgesic from the Thai medicinal herb Mitragyna speciosa".Life Sciences.74 (17):2143–2155.doi:10.1016/j.lfs.2003.09.054.PMID14969718.
^abKarunakaran T, Marimuthu Y, Rusmadi NN, Firouz NS, Jenis J, Kumar US, et al. (2024-10-10). "Chemistry and toxicity of 7-hydroxymitragynine (7-OHMG): an updated review on the oxidized derivative of mitragynine".Phytochemistry Reviews.24 (5):4051–4064.Bibcode:2025PChRv..24.4051G.doi:10.1007/s11101-024-10029-x.ISSN1572-980X.
^Matsumoto K, Horie S, Takayama H, Ishikawa H, Aimi N, Ponglux D, et al. (2005). "Antinociception, tolerance and withdrawal symptoms induced by 7-hydroxymitragynine, an alkaloid from the Thai medicinal herb Mitragyna speciosa".Life Sciences.78 (1):2–7.doi:10.1016/j.lfs.2004.10.086.PMID16169018.
