Valproic acid affects chemicals in the body that may be involved in causing seizures. Valproic acid is used to treat various types of seizure disorders. Valproic acid is sometimes used together with other seizure medications. Valproic acid is also used to treat manic episodes related to bipolar disorder (manic depression), and to prevent migraine headaches. Valproic acid may also be used for purposes not listed in this medication guide.