Perphenazine is a typical antipsychotic drug. Chemically, it is classified as a piperazinyl phenothiazine. Perphenazine is roughly five times as potent as chlorpromazine; thus perphenazine is considered a medium-potency antipsychotic. Perphenazine is used to treat psychosis. Perphenazine effectively treats the positive symptoms of schizophrenia, such as hallucinations and delusions, but its effectiveness in treating the negative symptoms of schizophrenia, such as flattened affect and poverty of speech, is unclear. Earlier studies found the typical antipsychotics to be ineffective or poorly effective in the treatment of negative symptoms, but two recent, large-scale studies found no difference between perphenazine and the atypical antipsychotics. Perphenazine has been used in low doses as a 'normal' or 'minor' tranquilizer in patients with a known history of addiction to drugs or alcohol, a practice which is now strongly discouraged.