Risperidone, sold under the brand name Risperdal among others, is an atypical antipsychotic[2] used to treat schizophrenia and bipolar disorder,[2] as well as irritability associated with autism.[9] It is taken either by mouth or by injection (i.e., subcutaneous or intramuscular).[2] The injectable versions are long-acting and last for 2–4 weeks.[10]
Also, the side effects include something called Tardive dyskinesia (TD)