Prazosin is used alone or in combination with other medications to treat high blood pressure. Prazosin is in a class of medications called alpha-blockers. It works by relaxing the blood vessels so that blood can flow more easily through the body.
Prazosin is also used to treat benign prostatic hyperplasia (BPH, noncancerous enlargement of the prostate), congestive heart failure, pheochromocytoma (adrenal gland tumor), sleep problems associated with post-traumatic stress disorder (PTSD; an anxiety disorder in people who experience or witness a traumatic, life-threatening event), and Raynaud’s disease (condition where the fingers and toes change skin color from white to blue to red when exposed to hot or cold temperatures). Talk to your doctor about the possible risks of using this medication for your condition.
Summary from MedlinePlus.gov, click for more information.