Ketanserin, sold under the brand name Sufrexal, is an antihypertensive agent which is used to treat arterial hypertension and vasospastic disorders.

[6][3] Side effects of ketanserin include dizziness, tiredness, edema, dry mouth, weight gain, and QT interval prolongation.

[18] A 2000 Cochrane Review found that, compared to placebo, ketanserin did not provide significant relief for people suffering from Raynaud's phenomenon attacks in the setting of progressive systemic sclerosis (an autoimmune disorder).

However, due to the significant adverse effect burden, the authors concluded that ketanserin's utility for this indication is likely unbeneficial.

However, now the drug is available as a topical gel formulation for treating wounds, burns, ulcers, and anal fissures.

[23] Increasing research into the use of psychedelics as antidepressants has seen ketanserin used to both block the hallucinogenic experience, and to disentangle the specific cognitive effects of 5-HT2A activation.

[24] Ketanserin has been found to block the psychedelic effects of psilocybin,[25] lysergic acid diethylamide (LSD),[26][27] mescaline,[28] and ayahuasca (dimethyltryptamine)[29] in clinical studies.