Direct vasodilators
Direct vasodilators relax the smooth muscle in artery walls, which widens the arteries and lowers blood pressure. Hydralazine is the main example and treats high blood pressure, including severe high blood pressure that needs to come down quickly. Headache, flushing, and a fast or pounding heartbeat are common because the body reacts to the drop in pressure. Long-term use can cause a lupus-like reaction with joint pain and fever, and these drugs are often combined with a beta blocker and a diuretic to offset the fast heartbeat and fluid retention.