BERKELEY, CA (UroToday.com) - Our initial study “Finasteride Use in the Male Infertility Population: Effects on Semen and Hormonal Parameters”, was published in Fertility and Sterility in 2013. In this study, we found that finasteride, even at low doses, caused reduced sperm counts in some infertile men. While only 27 men were taking finasteride in our cohort, sperm counts improved dramatically (mean 11.6 fold increase) following finasteride discontinuation.
The findings of our study could indicate that a very large number of men of reproductive years have sub-fertility related to the use of low-dose finasteride used to treat androgenic alopecia. Based on patient numbers quoted by an editorial response, it is estimated that 4.1 million men of reproductive age may take finasteride in the U.S. But it is important to emphasize that we do not yet know how many men have reduced sperm quality due to the use of low-dose finasteride. It is now clear, from both our study and other published work, that low-dose finasteride may reduce sperm counts and cause reduced fertility in some men.[2, 3, 4, 5] It is also clear that men with infertility and low sperm counts on finasteride should stop the finasteride. Sperm counts for most of these men with infertility and low sperm counts increase dramatically when the finasteride is stopped.
What is not clear is how frequently men who are taking low-dose finasteride have a reduction in sperm counts and fertility. Overstreet et al. found that most normospermic men taking low-dose finasteride did not have a reduction in any sperm parameters with the drug. Of note, a small percentage of the men in this study did have reduced sperm counts while taking low-dose finasteride. Overstreet's study  would suggest that the use of low-dose finasteride is unlikely to result in reduced sperm counts in men who initially have normal sperm parameters. However, this study excluded men with abnormalities in sperm parameters, potentially the very types of men who could have a greater sensitivity to the adverse effects of finasteride on fertility. We do not know the effect of low-dose finasteride on the sperm quality of these men with already compromised sperm parameters.
This study and other publications[2, 3, 4, 5] have identified an adverse effect of low-dose finasteride on fertility for some men. With what is known presently, we believe it is important that clinicians prescribing these medications be aware that there are some men in whom low-dose finasteride will have a negative effect on semen parameters. Clinicians should also be aware that finasteride should be stopped in infertile men or men with abnormal semen parameters. Unfortunately, we cannot yet predict which men on low-dose finasteride will develop abnormal semen parameters. Since finasteride is a widely used drug among men of reproductive years (likely to be of even wider use in the future), further studies using larger databases are essential to identify which men taking low-dose finasteride are at risk to develop infertility. In addition, whatever physiologically predisposes these men to developing finasteride-induced subfertility may also predispose them to developing other conditions.
- Hotaling JM. Finasteride and male infertility: a case for prospective collaborative research databases? Fertil Steril. 2013 Sep 14. PubMed PMID: 24044935.
- Samplaski MK, Lo K, Grober E, Jarvi K. Finasteride use in the male infertility population: effects on semen and hormone parameters. Fertil Steril. 2013 Dec;100(6):1542-6. PubMed PMID: 24012200.
- Glina S, Neves PA, Saade R, Netto NR, Jr., Soares JB, Galuppo AG. Finasteride-associated male infertility. Revista do Hospital das Clinicas. 2004 Aug;59(4):203-5. PubMed PMID: 15361986.
- Liu KE, Binsaleh S, Lo KC, Jarvi K. Propecia-induced spermatogenic failure: a report of two cases. Fertil Steril. 2008 Sep;90(3):849 e17-9. PubMed PMID: 18054928.
- Chiba K, Yamaguchi K, Li F, Ando M, Fujisawa M. Finasteride-associated male infertility. Fertil Steril. 2011 Apr;95(5):1786 e9-11. PubMed PMID: 21193189.
- Overstreet JW, Fuh VL, Gould J, Howards SS, Lieber MM, Hellstrom W, et al. Chronic treatment with finasteride daily does not affect spermatogenesis or semen production in young men. Journal of Urology. 1999 Oct;162(4):1295-300. PubMed PMID: 10492183.
Mary K. Samplaski, MD and Keith A. Jarvi, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Division of Urology, Department of Surgery, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada