3,4-Dihydroxymethamphetamine (HHMA, 3,4-DHMA), or 3,4-dihydroxy-N-methylamphetamine, also known as α-methylepinine or α,N-dimethyldopamine, is the major metabolite of 3,4-methylenedioxy-N-methylamphetamine (MDMA).

[1][2][3] It is formed from MDMA by O-demethylation via cytochrome P450 enzymes including CYP2D6 as well as CYP1A2 and CYP3A4.

[1][3] Like MDMA, HHMA is a monoamine releasing agent.

[4] Along with 3,4-dihydroxyamphetamine (HHA; α-methyldopamine), HHMA may be involved in the serotonergic neurotoxicity of MDMA.

[1][5][6][3] However, findings in this regard are conflicting, and the neurotoxicity of MDMA and related agents may instead be based on their mechanism of action without involvement of metabolites.