Prochlorperazine is an anti-psychotic medicine in a group of drugs called phenothiazines (FEEN-oh-THYE-a-zeens). It works by changing the actions of chemicals in your brain. Prochlorperazine oral (taken by mouth) is used to treat psychotic disorders such as schizophrenia. It is also used to treat anxiety, and to control severe nausea and vomiting. Prochlorperazine may also be used for purposes not listed in this medication guide.