Delusional infestation treated with risperidone: a series of 27 patients.

BACKGROUND: Patients with delusional infestation (DI) frequently refuse to be treated with psychoactive drugs. In the past, pimozide was commonly used as a first-line agent but is now prescribed more rarely. Risperidone was first used to treat DI in 1995. A recent review identified 12 studies that evaluated the use of risperidone in 43 patients with DI. OBJECTIVES: To study the characteristics of and therapeutic results in patients with DI treated with risperidone at a university medical centre in São Paulo, Brazil. METHODS: We performed a retrospective study of patients with DI treated with risperidone at a dermatological university clinic since 2016. Records were reviewed for personal data and findings related to treatment. RESULTS: Twenty-seven patients were studied (20 women and 7 men). The maintenance dose of risperidone varied from 1 mg three times weekly to 8 mg daily. Control of symptoms was achieved in the majority of patients. A reduction in dosage due to side-effects was seen in four patients; risperidone had to be switched to another antipsychotic in three cases, despite a good response. Only one patient did not respond to risperidone. CONCLUSIONS: Risperidone is an effective, well-tolerated and safe treatment for delusional parasitosis. Adequate follow-up is mandatory in order to obtain long-term control of symptoms.