Sexual side effects of medications for male pattern hair loss and prostate enlargement

A study just published in The Journal of Sexual Medicine documents the persistent sexual side effects of finasteride (Propecia, Proscar), a medication commonly used for both male pattern baldness and prostate hyperplasia, that too often are not discussed when prescribed. The authors observe:

"Finasteride has been associated with reversible adverse sexual side effects in multiple randomized, controlled trials for the treatment of male pattern hair loss (MPHL). The Medicines and Healthcare Products Regulatory Agency of the United Kingdom and the Swedish Medical Products Agency have both updated their patient information leaflets to include a statement that “persistence of erectile dysfunction after discontinuation of treatment with Propecia has been reported in post-marketing use.”"

They set out to...

"...characterize the types and duration of persistent sexual side effects in otherwise healthy men who took finasteride for MPHL,"...

...by investigating the new onset of sexual side effects lasting for at least 3 months despite discontinuing finasteride. What did their data show?

"Subjects reported new-onset persistent sexual dysfunction associated with the use of finasteride: 94% developed low libido, 92% developed erectile dysfunction, 92% developed decreased arousal, and 69% developed problems with orgasm...The mean duration of finasteride use was 28 months and the mean duration of persistent sexual side effects was 40 months from the time of finasteride cessation to the interview date."

The authors admonished practitioners in their conclusion to offer patients the courtesy of full disclosure:

"Physicians treating MPHL should discuss the potential risk of persistent sexual side effects associated with finasteride."

This report follows a study published earlier this year on persistent sexual side effects from finasteride and another 5α-reductase inhibitor (5α-RI), dutasteride, when used to treat urinary tract symptoms caused by prostate enlargement. They also stated:

"Prolonged adverse effects on sexual function such as erectile dysfunction and diminished libido are reported by a subset of men, raising the possibility of a causal relationship...We suggest discussion with patients on the potential sexual side effects of 5α-RIs before commencing therapy. Alternative therapies may be considered in the discussion, especially when treating androgenetic alopecia."

Clinicians reading this will know that 5α-reductase inhibitors block the conversion of testosterone to dihydrotestosterone (DHT). DHT is 10 times stronger in conferring androgen stimulation on tissues—the loss of male hormone effects is more precipitous with smaller reductions of DHT. It is important to note that the hormone measurements were not done for these patients. Other factors, and other hormones, including estrogen and insulin, also affect the prostate. In the functional approach to MPHL and prostate hyperplasia the bioactive free fractions of testosterone, DHT and estrogen, along with other analytes are always measured to determine (1) if DHT is actually too high (not always the case), and (2) if a natural or synthetic 5α-reductase inhibitor is used, to make sure that DHT is not reduced too much (by follow-up tests). Excessive reduction of testosterone receptor stimulation is a risk not only for sexual side effects but also depression, cardiovascular disease, sarcopenia (loss of muscle mass), osteoporosis and other ailments.