There are two types of medication that help to control the symptoms of an enlarged prostate; they are alpha blockers and finasteride Proscar, Propecia. Alpha blockers are effective in about 75% of men. They work by relaxing the muscles at the neck of the bladder making urination easier. The FDA has approved three types: doxazosin Cardura; tamsulosin Flomax and terazosin Hytrin. Finasteride actually shrinks the prostate gland and is found to be most effective in men whose prostate is significantly enlarged. It can take a long time for the drug to show improvement in symptoms - up to a year for complete results. Flomax is used to treat the symptoms of an enlarged prostate—a condition technically known as benign prostatic hyperplasia or BPH. The walnut-sized prostate gland surrounds the urethra (the duct that drains the bladder). If the gland becomes enlarged, it can squeeze the urethra, interfering with the flow of urine. This can cause difficulty in starting urination, a weak flow of urine, and the need to urinate urgently or more frequently. Flomax doesn't shrink the prostate. Instead, it relaxes the muscle around it.