Clonidine tablets (Catapres) are used alone or in combination with other medications to treat high blood pressure. Clonidine extended-release (long-acting) tablets (Kapvay) are used alone or in combination with other medications as part of a treatment program to control symptoms of attention deficit hyperactivity disorder (ADHD; more difficulty focusing, controlling actions, and remaining still or quiet than other people who are the same age) in children. Clonidine is in a class of medications called centrally acting alpha-agonist hypotensive agents. Clonidine treats high blood pressure by decreasing your heart rate and relaxing the blood vessels so that blood can flow more easily through the body. Clonidine extended-release tablets may treat ADHD by affecting the part of the brain that controls attention and impulsivity. High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.