Tamsulosin is in a class of drugs called alpha-adrenergic blockers. Tamsulosin causes the blood vessels (veins and arteries) to relax and expand, so that blood passes through them more easily. This effect relaxes the muscles in the prostate and bladder neck, making it easier to urinate.

Tamsulosin is used to treat benign prostatic hyperplasia (enlarged prostate).
Tamsulosin may also be used for purposes other than those listed in this medication guide.

Tamsulosin (tam-SOO-loh-sin) is used to treat the signs and symptoms of benign enlargement of the prostate (benign prostatic hyperplasia or BPH). Tamsulosin helps relax the muscles in the prostate and the opening of the bladder. This may help increase the flow of urine and/or decrease the symptoms. However, tamsulosin will not shrink the prostate. The prostate may continue to get larger. This may cause the symptoms to become worse over time. Therefore, even though tamsulosin may lessen the
problems caused by enlarged prostate now, surgery still may be needed in the future.

The a 1 -adrenoceptor antagonist, tamsulosin, is selective for a 1A - and a 1D - over a 1B -adrenoceptors. Both placebo-controlled and comparative studies with other agents have demonstrated tamsulosin to be an effective treatment for patients with lower urinary symptoms suggestive of benign prostatic hyperplasia. Its effectiveness appears to be maintained over many years. Tamsulosin may also effectively reduce lower urinary tract symptoms in other urological diseases. A dose of tamsulosin 0.4 mg/day has a tolerability close to that of placebo and has little, if any, blood pressure lowering effects.

You should not use this medicine if you have had an allergic reaction to tamsulosin or to similar medicines.