Carbamazeprine Hypersensitivity Syndrome (CBZ) is a reaction which occurs in 3-5% of patients taking phenytoin, a drug prescribed to stop convulsions or epileptic seizures.This article describes CBZ in a 13 year old who was admitted to the hospital for psychosis with suicidal/homicidal ideation. Phenytoin is often prescribed in patients believed to have bi polar disorder. Doctors warn that patients being treated with phenytoin should be observed for signs of CBZ-characterized by facial edema.