Used primarily to treat high blood pressure (hypertension) by relaxing blood vessels, allowing blood to flow more easily. Also prescribed for managing symptoms of benign prostatic hyperplasia (enlarged prostate) by relaxing muscles in the prostate and bladder neck. Investigated for use in post-traumatic stress disorder (PTSD) to reduce nightmares and improve sleep quality. Works by blocking alpha-1 receptors in smooth muscle, leading to vasodilation and reduced peripheral resistance.