Finasteride and Semen Quantity Reduction

Hello Doc..
What is the exact mechanism of finasteride to reduce the semen quantity? Does everyone who is taking finasteride face the problem of reduction in semen quantity to some extent or are there people who do not have any reduction in semen quantity??

People react differently to certain medications. There is a small percentage (1-2%) that sees a decrease in libido, however, there are others that see an increase. Along the same lines, some may have a decrease in semen volume (not uncommon), however, according to an article from October 1999 in the Journal of Urology titled “Chronic treatment with finasteride daily does not affect spermatogenesis or semen production in young men“, the authors concluded that, “Treatment with 1 mg. finasteride daily for 48 weeks did not affect spermatogenesis (sperm production) or semen production in young men.”

A more recent study does report two patients with decreased sperm counts.