Alpha blockers lower blood pressure by keeping the hormone norepinephrine from tightening the muscles in the walls of smaller arteries and veins. As a result, the vessels remain open and relaxed. This improves blood flow and lowers blood pressure.
Because alpha blockers also relax other muscles throughout the body, these medications also can help improve urine flow in older men with prostate problems.
Examples of alpha blockers
Alpha blockers are either short-acting or long-acting. Short-acting medications work quickly, but their effects last only a few hours. Long-acting medications take longer to work, but their effects last longer. The alpha blocker that's best for you depends on your health and the condition being treated.
Alpha blockers are also called alpha-adrenergic blocking agents, alpha-adrenergic antagonists, adrenergic blocking agents and alpha-blocking agents.
Examples of alpha blockers used to treat high blood pressure include:
- Doxazosin (Cardura)
- Prazosin (Minipress)
When alpha blockers are used
Alpha blockers typically aren't the first treatment option for high blood pressure. Instead, they're used in combination with other drugs, such as diuretics, when your high blood pressure is difficult to control.
In addition to high blood pressure, doctors prescribe alpha blockers to prevent, treat or improve symptoms of an enlarged prostate (benign prostatic hyperplasia).
Some alpha blockers might have a "first-dose effect." When you start taking an alpha blocker, you might develop pronounced low blood pressure and dizziness, which can make you faint when you rise from a sitting or lying position. As a result, the first dose is often taken at bedtime.
Other side effects might include:
- Pounding heartbeat
Before taking an alpha blocker, be sure your doctor knows about other medications you take, such as beta blockers, calcium channel blockers or medications for erectile dysfunction. Alpha blockers can increase or decrease the effects of other medications you take.
Alpha blockers may improve total cholesterol. However, some research has found that long-term use of some alpha blockers can increase the risk of heart failure.