Finasteride

A 40-year-old man experienced secondary infertility after using finasteride 1mg daily for 101 months (8.5 years) to treat hair loss from androgenetic alopecia. Laboratory tests revealed impaired semen parameters and a sperm DNA fragmentation index (SDFI) greater than 30%, indicating DNA damage. Upon discontinuing finasteride, his semen volume, count, and motility improved within 8 months, and his SDFI decreased. His wife became pregnant 11 months after he stopped taking the drug, and his semen parameters continued to improve 18 months after cessation. However, after the man restarted finasteride, follow-up tests at 3 months and 19 months showed a decline in semen volume, sperm count, and motility, although his SDFI was not affected. This case suggests that prolonged use of low-dose finasteride may cause reversible secondary infertility.