Prazocin 5mg Tablet ER is used to treat high blood pressure and lower your risk of having a heart attack or stroke. It may also be used to treat heart failure and mild enlargement of the prostate gland. Prazocin 5mg Tablet ER is an alpha blocker. It lowers blood pressure by relaxing blood vessels so that blood can flow more easily through the body. The tablet may be prescribed alone or in combination with other medicines. It can be taken with or without food. The dose will depend on your condition and how you respond to the medicine. Take this medicine regularly to get the most benefit. keep taking it even if you feel well. If you stop, your blood pressure may rise and put you at risk of heart attack or stroke. You may need to take it for the rest of your life. The most common side effects of this medicine include dizziness, headache, nausea, and unusual beating of the heart (palpitation). Most side effects disappear when you get used to the medicine. if any symptom persist let your doctor know. Follow the instruction given by doctor..