Quinidine may potentiate the atrioventricular-blocking effect of risperidone.
Risperidone may enhance the antihypertensive effect of antihypertensive drugs. Risperidone may antagonize the effects of levodopa and dopamine agonists. The long-term use of carbamazepine in combination with risperidone may potentiate the effects of risperidone. The use of clozapine with risperidone may increase the effects of risperidone. Because of the predominant central nervous system effects of risperidone, lower doses of risperidone must be used in combination with other centrally-acting drugs and alcohol. In all these cases, the dose should be adjusted.