4-Hydroxy-5-methoxytryptamine (4-HO-5-MeO-T) is a serotonergic neurotoxin of the tryptamine family.

[1][2] It is structurally related to the monoamine neurotransmitter serotonin (5-hydroxytryptamine; 5-HT).

[2][1] The drug is also a monoamine reuptake inhibitor.

[2][1] Its analogue 4,5-dihydroxytryptamine (4,5-DHT) is also a serotonergic neurotoxin.

[2][1] Rapid auto-oxidation of 4-HO-5-MeO-T and 4,5-DHT prevents them from being used as serotonergic neurotoxins in scientific research.