It works by relaxing the muscles around the bladder exit and prostate gland so urine is passed more easily. This helps empty the bladder completely and reduces the need to pass urine frequently or urgently in BPH. Tamsulin 0.4mg Tablet may cause excessive drowsiness with alcohol. Know more about what is Tamsulosin ? what are the side effects and its uses. Tamsulosin belongs to the class of alpha-blockers.Used for treatment of men with enlarged prostate, known as benign prostatic hyperplasia. Tamsulosin is an alpha-1A and alpha-1B adrenergic receptor antagonist used to treat benign prostatic hyperplasia, ureteral stones, prostatitis, and female voiding dysfunction. Flomax ( Tamsulosin Hydrochloride) may treat, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison and health resources.