Finasteride vs Dutasteride and Fertility: How 5α-Reductase Inhibitors Can Damage Sperm Quality Over Time

[madman]

Abstract​

INTRODUCTION AND OBJECTIVES:​

To compare the impact of finasteride and dutasteride on semen parameters in young men treated for androgenic alopecia and to evaluate whether the duration of 5α-reductase inhibitor therapy affects sperm quality and hormonal profiles.

METHODS:​

This single-center, randomized, controlled study enrolled 380 men aged 25–35 years who had been treated for androgenic alopecia with either finasteride 1 mg/day (n=190) or dutasteride 0.5 mg/day (n=190) for at least 3 months. Each drug group was further divided into five subgroups according to treatment duration: <6 months, 6–12 months, 13–18 months, 19–24 months, and >24 months. Serum total testosterone, FSH, and LH levels were measured, and semen analysis included semen volume, sperm concentration, total and progressive motility, morphology, vitality, and sperm DNA fragmentation. Statistical comparisons were performed using ANOVA and multivariate regression analyses, with p<0.05 considered significant.

RESULTS:​

Semen volume, total motility, progressive motility, and vitality significantly decreased with longer treatment duration in both finasteride and dutasteride groups. DNA fragmentation index (DFI) increased progressively with treatment length. The decline in semen parameters was more pronounced among men taking dutasteride, particularly after 18 months of continuous therapy. No significant differences were observed in sperm concentration or morphology. Serum total testosterone remained stable across all groups, while FSH and LH showed mild, non-significant increases.

CONCLUSIONS:​

Prolonged treatment with 5α-reductase inhibitors is associated with a time-dependent deterioration in semen quality, especially in sperm motility and DNA integrity. Dutasteride exerts a slightly greater suppressive effect than finasteride, likely due to its dual inhibition of type I and II 5α-reductase. Clinicians should exercise caution when prescribing these agents to young men who wish to maintain future fertility, and periodic semen monitoring is recommended during long-term therapy.