Vasodilators are medications that open (dilate) blood vessels. They work directly on the muscles in the walls of your arteries, preventing the muscles from tightening and the walls from narrowing. As a result, blood flows more easily through your arteries, your heart doesn't have to pump as hard and blood pressure is reduced.

Several vasodilators are available. Which one is best for you depends on your health and the condition being treated.

Examples of vasodilators include:

• Hydralazine (Apresoline)
• Minoxidil

Doctors prescribe vasodilators to prevent, treat or improve symptoms in a variety of conditions, such as:

• High blood pressure
• Preeclampsia or eclampsia
• Heart failure
• Pulmonary hypertension

Vasodilators are potent medications and are generally used only as a last resort, when other medications haven't adequately controlled your blood pressure.

These medications have a number of side effects, some of which require taking other medications to counter those effects.

Side effects include chest pain, rapid heartbeat, heart palpitations, fluid retention (edema), nausea, vomiting, dizziness, flushing, headache, nasal congestion and excessive hair growth. In addition, some vasodilators can increase your risk of developing lupus, a connective tissue disease.