Vasodilators are medications that open (dilate) blood vessels. They affect the muscles in the walls of your arteries and veins, preventing the muscles from tightening and the walls from narrowing.
As a result, blood flows more easily through your vessels. Your heart doesn't have to pump as hard, reducing your blood pressure.
Some drugs used to treat hypertension, such as calcium channel blockers — which prevent calcium from entering blood vessel walls — also dilate blood vessels. But the vasodilators that work directly on the vessel walls are hydralazine and minoxidil.
Uses for vasodilators
Doctors prescribe vasodilators to prevent, treat or improve symptoms in a variety of conditions, such as:
- High blood pressure
- High blood pressure during pregnancy or childbirth (preeclampsia or eclampsia)
- Heart failure
- High blood pressure that affects the arteries in your lungs (pulmonary hypertension)
Side effects and cautions
Direct vasodilators are strong medications that generally are used only when other medications haven't controlled your blood pressure adequately.
These medications have a number of side effects, some of which require taking other medications to counter.
Side effects include:
- Rapid heartbeat (tachycardia)
- Heart palpitations
- Fluid retention (edema)
- Excessive hair growth
- Joint pain
- Chest pain