Side effects and cautions

Some alpha blockers might have what's called 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:

• Headache
• Pounding heartbeat
• Weakness
• Dizziness
• Weight gain

On the positive side, alpha blockers might decrease low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol).

Alpha blockers can increase or decrease the effects of other medications you take. 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.

Some research has found that long-term use of some alpha blockers can increase the risk of heart failure. More research is needed to confirm this finding.