Finasteride Linked With Lower Sperm Counts in Some Men

September 27, 2013

By Will Boggs, MD

NEW YORK (Reuters Health) Sep 27 - The use of finasteride is associated with lower sperm counts in some men, according to results from a prospective database study.

"Physicians should be aware that finasteride may cause infertility and should counsel men of reproductive years about this potential side effect of the medication," Dr. Keith Jarvi from University of Toronto, Canada, told Reuters Health by email.

"If the men are taking finasteride and have abnormal sperm parameters, the finasteride should be stopped," he said. "Fortunately, most men with low sperm counts who stop finasteride will have dramatic improvements in their semen parameters."

Originally approved to treat benign prostatic hyperplasia, finasteride has seen increasing use since its approval in 1997 to treat male-pattern baldness. The U.S. Food and Drug Administration has not reported any adverse effects of finasteride on male fertility.

Dr. Jarvi and his colleagues used prospectively collected data to examine semen and hormone parameters in 24 men on finasteride (mean dose, 1.04 mg/day, for an average of 57.4 months) who presented for fertility evaluation.

Most men (23) had semen and hormone testing while on finasteride alone (mean dose, 1.04 mg/day, for an average of 57.4 months), and 14 had testing while taking the drug and after discontinuation, the researchers report online September 5 in Fertility and Sterility.

Hormone profiles (FSH, LH, and testosterone) were similar when comparing nine men taking finasteride and eight men who had stopped taking it. Only one man, though, had hormone levels measured before and after discontinuation of finasteride.

In the 14 men who had semen analysis while taking finasteride and after discontinuing finasteride, the mean sperm concentration increased significantly from 13.2 million/mL to 42.25 million/mL (p=0.003).

Mean ejaculate volume did not differ before and after finasteride discontinuation, but sperm counts rose 11.6-fold on average, with the most dramatic increases occurring among men with severe oligospermia.

No man experienced a decrease in sperm count after cessation of finasteride.

"Finasteride likely affects the fertility in only a small fraction of the men using this medication for androgenic alopecia," Dr. Jarvi said. "But if these men on finasteride are experiencing low sperm counts, it is either hairless or infertile!"

"Most of our men hated going off finasteride and were worried about hair loss," Dr. Jarvi said. "Sometimes it took a lot of convincing before the men agreed to stop the finasteride. This kind of article will provide a solid basis for the physicians to impress on the man that finasteride may be the cause of his infertility and stopping finasteride is a reasonable approach to try to optimize the fertility for men with abnormal sperm parameters."

It's not the first time finasteride has been tied to fertility problems. Dr. Sidney Glina, who published a study suggesting such a link in 2004, called finasteride "a safe drug."

"However, if the patient has any other risk factor for infertility, such as varicocele or obesity, the drug can amplify the effect and can impair the spermatogenesis," Dr. Glina, from Albert Einstein Jewish Hospital in Sao Paolo, Brazil, told Reuters Health by email. "This possible effect must be stressed by doctors to men."

Dr. Glina added, "It is important to discontinue finasteride in any man who presents with an abnormal semen analysis and infertility before any other treatment. The negative effect is reversible in most of the cases."

In its prescribing information for finasteride, which it markets as Proscar for symptomatic benign prostatic hyperplasia, Merck writes, "Treatment with Proscar for 24 weeks to evaluate semen parameters in healthy male volunteers revealed no clinically meaningful effects on sperm concentration, mobility, morphology, or pH. A 0.6 mL (22.1%) median decrease in ejaculate volume with a concomitant reduction in total sperm per ejaculate was observed. These parameters remained within the normal range and were reversible upon discontinuation of therapy with an average time to return to baseline of 84 weeks."


Fertil Steril 2013.


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