Central-acting agents lower your heart rate and reduce your blood pressure. They work by preventing your brain from sending signals to your nervous system to speed up your heart rate and narrow your blood vessels. As a result, your heart doesn't pump as hard and your blood flows more easily through your blood vessels.

Central-acting agents are also called central adrenergic inhibitors, central alpha agonists and central agonists. Several central-acting agents are available. Which one is best for you depends on your health and the condition being treated.

Examples of central-acting agents include:

• Clonidine (Catapres)
• Guanfacine (Tenex)
• Methyldopa

Doctors prescribe central-acting agents to prevent, treat or improve symptoms in a variety of conditions, such as:

• High blood pressure
• Panic attacks
• Hot flashes
• Alcohol or drug withdrawal

These medications can have strong side effects, so they aren't commonly used. Side effects include extreme fatigue, drowsiness or sedation, dizziness, impotence, constipation, dry mouth, headache, weight gain, impaired thinking and psychological problems, such as depression.

Abruptly stopping use of some central-acting agents can cause a sudden, dangerous increase in blood pressure. Don't stop taking these medications without talking to your doctor.