Get emergency medical help if you have any of these signs of an allergic reaction to terazosin: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects:
fast or pounding heartbeats or fluttering in your chest;
feeling like you might pass out;
swelling in your hands, ankles, or feet; or
penis erection that is painful or lasts 4 hours or longer.
Less serious terazosin side effects may include:
mild dizziness;
weakness, drowsiness;
blurred vision;
nausea; or
headache.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Terazosin side effects (more detail)
