Does finasteride (a 5-alpha-reductase inhibitor) affect sperm quality and quantity in individuals trying to conceive?

Finasteride and Male Fertility: Effects on Sperm Quality During Conception Attempts

Finasteride can be continued in men trying to conceive, as it does not cause clinically meaningful harm to sperm parameters or offspring outcomes, though it does cause a reversible reduction in ejaculate volume. 1

Evidence from FDA Drug Labeling

The FDA label for finasteride provides the most authoritative guidance on this question:

• Treatment with finasteride for 24 weeks revealed no clinically meaningful effects on sperm concentration, mobility, morphology, or pH in healthy male volunteers. 1

• A median decrease of 0.6 mL (22.1%) in ejaculate volume with a concomitant reduction in total sperm per ejaculate was observed, but these parameters remained within the normal range and were reversible upon discontinuation with an average time to return to baseline of 84 weeks. 1

• Postmarketing reports of male infertility and/or poor seminal quality have been documented; however, normalization or improvement of seminal quality has been reported after discontinuation of finasteride. 1

Clinical Context and Practical Considerations

The key distinction is between statistical changes and clinical significance:

• While finasteride causes measurable reductions in ejaculate volume and total sperm count, the values typically remain within fertile ranges for men with normal baseline spermatogenesis. 1, 2

• In young men (ages 19-41), 1 mg finasteride daily for 48 weeks showed no significant effects on sperm concentration, total sperm per ejaculate, sperm motility, or morphology. 2

• The ejaculate volume decrease was minimal (-0.03 mL difference from placebo, representing only 1% difference). 2

Important Caveats for Men with Pre-existing Fertility Issues

Men with already impaired spermatogenesis may experience more pronounced effects:

• Case reports demonstrate that in subfertile patients with baseline oligospermia, finasteride may further decrease sperm parameters. 3, 4

• One case showed severe oligospermia 3 months after finasteride cessation in a man who had used it for 10 years, though sperm concentration improved within 1-2 months after stopping, leading to spontaneous conception. 3

• Another case documented azoospermia in a patient with pre-existing oligospermia; sperm concentration improved to >10 × 10⁶/mL within 16 weeks of discontinuation. 4

Recent Research Findings

A 2020 study provides additional nuance:

• At 6 months of treatment, statistically significant worsening of total sperm number (232.4 ± 160.3 vs. 133.2 ± 82.0; p = 0.01) and abnormal forms (79.8 ± 6.0 vs. 82.7 ± 5.7; p < 0.05) was detected. 5

• However, sperm parameters returned to near-baseline levels by 12 months of treatment and 1 year after discontinuation. 5

• Testosterone levels actually increased during treatment (22.1 ± 7.1 vs. 28.0 ± 8.0 ng/mL; p < 0.05). 5

Clinical Recommendations

For men with normal baseline fertility attempting conception:

• Finasteride can be continued without significant concern for offspring outcomes or fertility. 1, 2

• The reduction in ejaculate volume is the only established causal relationship between finasteride and reproductive parameters, and this does not typically affect fertility. 6

For men with pre-existing subfertility or oligospermia:

• Consider discontinuing finasteride 3-6 months before attempting conception to allow for recovery of spermatogenesis. 3, 4

• Perform baseline semen analysis before starting finasteride if fertility is a near-term concern. 5

• Monitor semen parameters if conception attempts are unsuccessful while on finasteride. 4

Regarding general male preconception care:

• Assess medications and conditions that may affect fertility at wellness visits when pregnancy is desired. 7

• Conduct physical examination for conditions affecting fertility and address modifiable risk factors (smoking, obesity, substance abuse). 7

Comparison to Other Medications

Finasteride is notably safer for male fertility than many other medications:

• Unlike cyclophosphamide, which causes dose-related permanent infertility requiring fertility preservation counseling, finasteride's effects are reversible. 7

• The 2025 EULAR guidelines list numerous antirheumatic drugs that can be continued in men trying to conceive, demonstrating that medication continuation during conception attempts is acceptable when evidence supports safety. 7