Catapres (clonidine hydrochloride) is an oral medication used primarily for the treatment of high blood pressure. It is also used to treat severe menstrual cramps, hot flashes during menopause, Tourette's syndrome, anxiety disorder, panic disorder, attention deficit hyperactivity disorder (ADHD), and alcohol and opiate (narcotic) withdrawal. It is in a class of medications called centrally acting alpha-agonist hypotensive agents, and works by decreasing the amount of blood the heart pumps out and by decreasing resistance in the blood vessels.