Tamsulosin belongs to a class of medications called alpha blockers. It works by relaxing the muscles in the prostate and bladder so that urine can flow easily. Tamsulosin capsules are used in men to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia or BPH) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency.