A healthcare provider may prescribe Risperdal^® (risperidone) to treat schizophrenia, bipolar disorder, or irritability due to autism. The medication works by blocking or lessening the effects of several chemicals in the brain. Risperdal comes in the form of a tablet and is usually taken once or twice a day. The drug is also available as a liquid, orally disintegrating tablets, and as an injection. As with any drug, there are possible side effects with Risperdal, including drowsiness, upper respiratory tract infections, and increased salivation. Among the conditions that you should let your healthcare provider know about before you take Risperdal are diabetes, epilepsy, and liver or kidney disease.