Clonidine is a medication commonly used to lower blood pressure. It may be effective on its own, or be used in conjunction with other medication. It works by relaxing the walls of the blood vessels and slowing the heart rate. Clonidine requires a prescription and may not be purchased over-the-counter. It most commonly comes in the form of a pill. In some cases it may come in the form of a transdermal patch or epidural injection. Clonidine HCl is used in treating high blood pressure or hypertension. It is a central alpha antagonist drug that works to lower blood pressure. Clonidine HCl helps to keep the blood vessels dilated or widened to reduce the pressure of blood in the arteries. By expanding the blood vessels, the pressure will be normalized, and hypertension conditions will be treated. Clonidine HCl can be used to treat other conditions associated with blood pressure such as angina. By treating high blood pressure, stroke and heart attack risks are also reduced. Clonidine HCl is supplied in the form of suspension and should be taken by mouth after shaking well. The common side effects of this drug are vomiting, dizziness, stomach upset, and pale skin.