Terazosin hydrochloride, used in the treatment of benign prostatic hyperplasia, is also used in the treatment of hypertension, either alone or in combination with other antihypertensive drugs. Terazosin hydrochloride is a selective alpha 1 receptor blocker that reduces peripheral vascular resistance and has a lowering effect on both systolic and diastolic blood pressure. It is usually not accompanied by tachycardia and has no adverse effects on electrolytes, blood glucose, liver and kidney functions, and has some improvement on blood lipids. It can selectively block smooth muscle α1 receptors in the bladder neck, prostate body and peritoneum, thus reducing smooth muscle tone, decreasing lower urinary tract resistance and relieving symptoms such as urinary frequency, urinary urgency and difficulty in urination due to prostate enlargement.