Propecia and Sperm Count

Dear Dr. Rassman.

What current info do you have on the possibility of finasteride reducing sperm count? Are there any scientific studies out there on this subject? I will be planning on starting a family in the next year or two and fear such side effects will greatly harm my chances of conception.

You have stated that finasteride in a dose of 0.5mg is around 70-80% as effective as 1mg. Can you give an answer as to how effective you think a 0.25mg dose would be in comparison to 1mg? After only 5 days of taking a quartered proscar pill, I’m experiencing some side effects such as increased libido and problems in maintaining an erection. I have no problems getting an erection (due to the increase of libido), just maintaining it.

I’ve heard that taking zinc in high doses can significantly lower DHT levels. Can you shed more light on this subject?

Warmest Regards

Finasteride (Propecia) may cause a decrease in volume of semen, but there is no evidence that the medication causes low sperm count in men. In animal studies, mature rats treated with very high doses of finasteride (488 times the usual human exposure) for up to 12 weeks did not demonstrate any adverse effect on fertility or ejaculate volume. However, when treatment was continued for 24 to 30 weeks, fertility rate decreased significantly in those animals. Diminished fertility was entirely reversible within 6 weeks of discontinuation of the medication in all animals.

The above mentioned study was performed with very high doses of finasteride. The occurrence of decreased fertility should be much less if any in usual doses in human. If you are still concerned about fertility, stop finasteride and the potential adverse effect of the medication should be eliminated in days.

About the effect of lower doses of finasteride, there is not enough evidence on lower doses to absolutely confirm value. We suspect the lower doses may still have a good effect based on animal studies. I can not give you an exact number for this until it is proven by scientific studies on humans. There is no evidence that fertility is impacted by finasteride so this woman on the right could have been your wife.

Regarding the last part of your question; treatment with zinc has been studied in 37 patients with infertility. Administration of zinc has increased DHT with no effect on testosterone or fertility. The mechanism of this effect is not clear. And we don’t have any evidences that zinc supplement can increase hair growth in people who are not zinc deficient.