Sagent Pharmaceuticals Haloperidol Lactate Injection 1 mL Single Dose Vial is a first generation butyrophenone antipsychotic agent that works by blocking dopamine receptors in the brain. This medication is used to treat symptoms of schizophrenia and other psychotic disorders. Haloperidol lactate injection is also used to control severe behaviors associated with autism. It is important to note that haloperidol may cause side effects such as restless legs syndrome, akathisia (restlessness), tardive dyskinesia (involuntary muscle movements), and neuroleptic malignant syndrome (a life-threatening reaction).