Dextrorphan (DXO) is a psychoactive drug of the morphinan class which acts as an antitussive or cough suppressant and in high doses a dissociative hallucinogen.

Dextrorphan has a notably longer elimination half-life than its parent compound, and therefore has a tendency to accumulate in the blood after repeated administration of normally dosed dextromethorphan formulations.

[9] Dextrorphan was formerly a Schedule I controlled substance in the United States, but was unscheduled on October 1, 1976.

[11] In 2021, dextrorphan was identified in >75% of sludge samples taken from 12 wastewater treatment plants in California.

The same study associated dextrorphan with estrogenic activity by using predictive modelling, before observing it in in vitro.