Alpha- and Beta-blockers: They work on the nervous system to relax the blood vessels and slow down the heart rate.
ACE (angiotensin-converting enzyme) inhibitors and Angiotensin receptor blockers: They block hormones that constrict blood vessels.
Calcium channel blockers: By barring calcium from entering the muscle cells of the heart and blood vessels, they make the vessels relax.
Central nervous system inhibitors: By controlling nerve impulses, they relax the blood vessels.
Vasodilators: They open blood vessels by directly relaxing the muscle in the vessel walls.