What are the major side effects of pimozide?

• Anticholinergic effects: Dry eyes, dry mouth, constipation, urinary retention
• Extrapyramidal symptoms: Dystonia (muscle spasm), akathisia (motor restlessness), Parkinsonian-like syndrome (characterized by a pill-rolling tremor, rigidity, stiffened gait, and flattened facial expression)
• Antiadrenergic effects: Orthostatic hypotension
• Tardive dyskinesia: Less common

In addition to having these side effects, pimozide is a calcium channel blocker with the potential to alter cardiac conduction and prolong the QT interval. Although the medication is usually used only in small doses, patients should be followed closely for any adverse effects. A baseline electrocardiogram (ECG) should be obtained and repeated after initiation of therapy and periodically with dose increases.

Lorenzo CR, Koo J: Pimozide in dermatologic practice: a comprehensive review, Am J Clin Dermatol 5:339–349, 2004.