Blocking muscarinic receptors produce blurring of vision and increased intraocular pressure, dry mouth and eyes, constipation and urinary retention. Acetylcholine acts in opposition to DA in basal ganglia and it is possible that the relative lack of extrapyramidal side-effects with clozapine and thioridazine results from their high antimuscarinic potency.

Blocking á-adrenoreceptors results in the important side-effect in humans of orthostatic hypotension.