An unreported side effect of risperidone in children: sinus arrest with long pauses causing syncope.

Risperidone has been reported as a well-tolerated antipsychotic in children. The most common side effects of risperidone are anxiety, headaches, insomnia, and agitation, which frequently appear with high doses. Although it is known that risperidone affects the cardiac conduction system, symptomatic bradycardia has not been reported previously in children. We report a child who developed syncope because of sinus arrest with long pauses (>3 seconds) with therapeutic doses of risperidone. This case suggests that close monitoring is mandatory even during therapeutic treatment with risperidone.