Desmetramadol (INNTooltip International Nonproprietary Name), also known as O-desmethyltramadol (O-DSMT), is an opioid analgesic and the main active metabolite of tramadol.

Desmetramadol is commonly encountered as a designer drug online[4] in powder form or as an ingredient in pressed pills due to being unscheduled in many jurisdictions.

Outside of its role as a metabolite, a chemical used in research, and as a recreational drug, desmetramadol has a very limited history of human usage and is not approved for medicinal use in any country as of 2025.

The potential selectivity and favorable side effect profile of desmetramadol compared to tramadol, makes it more suitable for use as antidepressant, although clinical development appears to have stopped.

Human clinical trials have shown it to offer similar analgesic benefits to drugs such as oxycodone and fentanyl but with reduced respiratory depression and a comparatively favorable safety profile.