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

BACKGROUND: Patients with delusional infestation frequently refuse to be treated with psychoactive drugs. Pimozide was commonly used as a first-line agent; recently, it has been prescribed more rarely; risperidone was first used in 1995. A recent review identified 12 studies evaluating risperidone, with a total of 43 patients.

OBJECTIVE: To study the characteristics and therapeutic results in patients with delusional infestation treated with risperidone in a university medical center in São Paulo, Brazil.

METHODS: We performed a retrospective study of patients with delusional infestation treated with risperidone in a dermatological university clinic since 2016. Records were reviewed for personal data, and findings related to treatments.

RESULTS: Twenty-seven patients were studied (20 female: 7 male). Maintenance dose of risperidone varied from 1 mg 3 times a week to 8 mg daily. Control of symptoms was achieved in the majority of patients. Reduction in dosage due to side effects occurred in four patients; risperidone had to be switched to another antipsychotic in three cases despite of good response. Only one patient did not respond to risperidone.

CONCLUSION: 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.