Prochlorperazine or 'Stemetil' is one of a number of drugs called phenothiazine. Prospective and retrospective cohort studies, case-control, and record linkage studies of patients with exposure to various and multiple phenothiazines have failed to demonstrate an increased risk of major malformations. It was found to be effective for nausea and vomiting in pregnancy in 3 randomised controlled trials in severe nausea and vomiting in pregnancy (Hyperemesis Gravidarum). Side effects include drowsiness, restlessness and occasional extra pyramidal effects (Such as tremor, slurred speech, anxiety, distress and others). These are prescription only medications.