Terazosin is in a class of drugs called alpha-adrenergic blockers. Terazosin causes the blood vessels (veins and arteries) to relax and expand, which allows blood to pass more easily through them. Terazosin relaxes the smooth muscles of the arteries, the prostate, and the bladder neck. Relaxing the smooth muscles of the arteries lowers blood pressure. Relaxing the smooth muscles around the bladder neck relieves urinary obstruction caused by an enlarged prostate (prostate hypertrophy). Captopril is used to treat high blood pressure and heart failure. It decreases certain chemicals that tighten the blood vessels, so blood flows more smoothly and the heart can pump blood more efficiently.
Terazosin is used to treat the symptoms of urinary obstruction as a result of an enlarged prostate. Terazosin relaxes the smooth muscles of the bladder neck and the prostate and increases urine flow. Terazosin is also used alone or in combination with another blood pressure medication to treat high blood pressure. Terazosin is also used for the treatment of enlarged prostate (benign prostatic hypertrophy or BPH). For BPH, terazosin helps to relax the muscles in the prostate and bladder. This helps to improve urine flow and decrease symptoms of BPH. Terazosin does not slow or stop the progression of enlarged prostate.