From the Guidelines
Approximately 4.2-15.8% of men experience erectile dysfunction when taking finasteride for hair loss, with the highest quality study suggesting a rate of 15.8% in the PROSPECT trial 1. Finasteride, commonly prescribed as Propecia at 1mg daily for hair loss, works by inhibiting the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT), a hormone linked to male pattern baldness. While this mechanism effectively reduces hair loss, it can affect sexual function in some men. The sexual side effects, including ED, decreased libido, and ejaculation disorders, typically resolve after discontinuing the medication, though in rare cases they may persist. Some key points to consider include:
- The risk of sexual side effects appears to be dose-dependent, with higher doses (such as the 5mg used for prostate conditions) associated with greater risk than the 1mg dose used for hair loss 1.
- Men considering finasteride should discuss these potential side effects with their healthcare provider, especially if they have pre-existing sexual dysfunction or concerns.
- Alternative hair loss treatments like minoxidil (Rogaine) don't carry the same risk of sexual side effects and might be preferable for men concerned about this potential adverse effect. The highest quality study, the PROSPECT trial, reported an erectile dysfunction rate of 15.8% in men taking finasteride for hair loss 1. It's essential to weigh the benefits of finasteride for hair loss against the potential risks of sexual side effects and discuss these with a healthcare provider before starting treatment. In terms of treatment duration, the PCPT trial, which is the most reliable trial for directly comparing the benefits and harms of finasteride, administered the medication for a planned 7 years 1. However, the question of treatment duration required for the best outcome is still being researched, with an ongoing trial comparing dutasteride with placebo for preventing prostate cancer, where dutasteride is administered for 4 years 1.
From the FDA Drug Label
The incidence rates of drug-related adverse experiences reported by ≥2% of patients in any treatment group in the MTOPS Study are listed in Table 2 ... Urogenital ... Impotence 12.2 14.4 18.5 22.6
The percentage of men experiencing erectile dysfunction (impotence) with finasteride for hair loss is 18.5% 2.
From the Research
Erectile Dysfunction with Finasteride for Hair Loss
- The percentage of men experiencing erectile dysfunction with finasteride for hair loss is reported in several studies.
- A study published in 1999 3 found that the overall incidence of sexual function disorders, including erectile dysfunction, was 3.8% in finasteride recipients compared to 2.1% in placebo recipients.
- Another study published in 2012 4 reported that 20% of subjects with male pattern hair loss experienced persistent sexual dysfunction, including erectile dysfunction, for ≥6 years despite discontinuation of finasteride.
- A 2017 study 5 found that 1.4% of men exposed to finasteride developed persistent erectile dysfunction, with a median persistence of 1,348 days after stopping the medication.
- A 2016 study 6 reported that the rate of persistent sexual dysfunction, including erectile dysfunction, was 37.9 per 1000 person-years in finasteride users, with a mean time to first event of 391 days after discontinuation.
- A 2022 review 7 noted that the most commonly reported sexual events with finasteride include erectile dysfunction and decreased libido, and that patients need to be educated about the possible short- and long-term side effects.
Risk Factors and Duration of Use
- The 2017 study 5 found that longer duration of finasteride exposure increased the risk of persistent erectile dysfunction, with men exposed for >208.5 days having a 4.8-fold higher risk than those with shorter exposure.
- The 2016 study 6 reported that the risk of persistent sexual dysfunction was higher in men who stopped finasteride therapy, with an adjusted hazard ratio of 1.62 compared to omeprazole users.
- The 2022 review 7 noted that increasing patient complaints and analysis of the FAERS database led to the inclusion of depression in the FDA label in 2011, as men were found to be at a risk of suicide due to the persistent sexual side effects.