Finasteride is now the main drug used to treat prostate enlargement in older men and should be taken for a long time. Prostate enlargement is a common and frequent disease in elderly men, the causes are many, one of the main reasons, it is believed that the conversion of testosterone into dihydrotestosterone increases in elderly men, dihydrotestosterone can make the prostate volume increase. Finasteride is a 5α-reductase inhibitor that inhibits the conversion of testosterone to dihydrotestosterone, and the level of dihydrotestosterone decreases, reducing the size of the prostate and alleviating the symptoms of prostate enlargement. But this drug takes 3 months to work and must be taken for a long time, if you stop using it, the size of the prostate will increase again.