Ketanserin reverses the acute response to LSD in a randomized, double-blind, placebo-controlled, crossover study in healthy subjects.

These findings are consistent with an interaction between ketanserin and LSD and the view that LSD produces its psychedelic effects only when occupying 5-HT2A receptors. Ketanserin can effectively be used as a planned or rescue option to shorten and attenuate the LSD experience in humans in research and LSD-assisted therapy.