Clonidine is a medication that belongs to the class of medicines called antihypertensives. It is used to treat high blood pressure by decreasing heart rate and relaxing blood vessels so that blood can flow more easily through the body. Clonidine is also used in combination with other medications to control symptoms of attention deficit hyperactivity disorder (ADHD) in children. It may treat ADHD by affecting the part of the brain that controls attention and impulsivity. Clonidine is also used in the treatment of dysmenorrhea (severely painful cramps during menstrual period), hypertensive crisis (a condition in which your blood pressure is very high), Tourettes syndrome (a condition characterized by the need to perform repeated motions or to repeat sounds or words), menopausal hot flashes, and alcohol and opiate (narcotic) withdrawal. Clonidine is also used as an aid in smoking cessation therapy and to diagnose pheochromocytoma (a tumor that develops on a gland near the kidneys and may cause high blood pressure and fast heart rate). Clonidine is prescribed by various clinicians, including primary care providers, cardiologists, psychiatrists, and internists.