Frequently prescribed alpha blockers include doxazosin, brand name Cardura; tamsulosin, brand name Flomax; phentolamine, brand name OraVerse; and terazosin, brand name Hytrin, notes About.com. Alpha blockers are used to treat high blood pressure, symptoms associated with an enlarged prostate, peripheral artery disease and a hormone-secreting tumor called a pheochromocytoma.
Alpha blockers are generally well-tolerated, explains Mayo Clinic. Headaches, nausea, weight gain and weakness are among the most common side effects of this class of drugs. These drugs may also cause a pounding heartbeat and a small decrease in LDL or bad cholesterol.
Alpha blockers come with a specific warning regarding a phenomenon called first-dose effect, states Mayo Clinic. When alpha blockers are first started, they can cause significant dizziness and low blood pressure, resulting in faintness during position changes. Taking the first dose at bedtime reduces the chance of fainting with movement. Long-term use of alpha blockers is associated with an increased risk of heart failure.
This class of medication works by targeting alpha receptors, which are found in blood vessels, in the prostate gland and in baroreceptors, which are specialized blood pressure sensors, according to About.com. Specifically, alpha blockers relax small arteries and veins by blocking the action of norepinephrine in the body, notes Mayo Clinic.