2-Oxo-3-hydroxy-LSD, or 2-oxy-3-hydroxy-LSD, also known as O-H-LSD or OH-LSD, as well as more fully as 2-oxo-3-hydroxy-2,3-dihydro-LSD, is a lysergamide and the major metabolite of the psychedelic drug lysergic acid diethylamide (LSD). LSD is eliminated 13% as O-H-LSD in urine within 24hours and urinary concentrations of O-H-LSD are 4 to 40times those of LSD in humans.
The specific enzymes responsible for the formation of O-H-LSD from LSD are unclear. However, subsequent research found involvement of several cytochrome P450 enzymes. O-H-LSD is thought to form from other LSD metabolites like 2-oxo-LSD and 3-hydroxy-LSD.
It is unknown whether O-H-LSD is pharmacologically active or produces hallucinogenic effects. However, O-H-LSD showed profoundly reduced albeit still detectable activity at the serotonin 5-HT<sub>2</sub> receptors, including the serotonin 5-HT<sub>2A</sub>, 5-HT<sub>2B</sub>, and 5-HT<sub>2C</sub> receptors, compared to LSD in vitro.
O-H-LSD was first described in the scientific literature by at least the 1990s. It started being sold online as an analytical standard by 2024.