Question explored with the scientific record
What percent of those who take finasteride suffer sexual dysfunxtion
The honest answer: the percentage depends entirely on which study you read, and the range is wide.
The best randomized trial data for hair loss shows finasteride roughly doubles the risk of sexual side effects compared to placebo, but the absolute numbers are modest. One meta-analysis of 11 trials found a 1.66-fold higher risk of overall sexual adverse effects and nearly 2-fold higher risk of erectile dysfunction [1]. In a 4-year BPH trial, 15% of finasteride users reported sexual side effects in year one versus 7% on placebo [1]. Other reviews put erectile dysfunction at 3-16% and decreased libido at 2-10% [5].
But there is a darker subset the trials undercount. Studies of men who report persistent problems after stopping the drug show very high rates: 92-94% report low libido or erectile dysfunction [2], and 87% report loss of penis sensitivity [4]. One large electronic medical record study found 1.4% of all exposed men developed persistent erectile dysfunction lasting a median of 1,348 days after stopping, with young finasteride users facing a 4.9-fold higher risk with longer use [3].
| Measure | Finasteride | Placebo |
|---|---|---|
| Sexual side effects, year one (BPH trial) | 15% | 7% |
| Erectile dysfunction (trial range) | 3-16% | lower |
| Persistent ED after stopping (EMR cohort) | 1.4% | not measured |
The trials were mostly manufacturer-funded and short-term. The persistent-symptom studies recruited from online forums, so they overstate prevalence among all users. The truth is probably between: roughly 3-15% during use, with a small but real fraction, maybe 1-2%, experiencing long-term problems. The evidence does not support the "rare and reversible" claim you will hear from prescribers.
My call: finasteride causes sexual dysfunction in a meaningful minority, and the risk of persistent symptoms is real but smaller. Confidence: moderate.
Sources used 5
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Finasteride and Dutasteride for the Treatment of Male Androgenetic Alopecia: A Review of Efficacy and Reproductive Adverse Effects
This narrative review finds finasteride and dutasteride are effective for male AGA, with dutasteride more efficacious; sexual adverse effects are increased versus placebo but generally reversible, while persistent post-finasteride symptoms and sperm effects remain controversial.
DOI: 10.52504/001c.88531 -
Persistent Sexual Side Effects of Finasteride for Male Pattern Hair Loss
A subset of otherwise healthy men taking finasteride for male pattern hair loss reported persistent sexual side effects lasting years after stopping the medication, including high rates of low libido, erectile dysfunction, decreased arousal, and orgasm problems.
DOI: 10.1111/j.1743-6109.2011.02255.x -
Persistent erectile dysfunction in men exposed to the 5α-reductase inhibitors, finasteride, or dutasteride
In a large EMR cohort, longer 5a-reductase inhibitor exposure was associated with persistent erectile dysfunction lasting a median of about 1,348 days after stopping, including a 4.9-fold higher risk among young finasteride users.
DOI: 10.7717/peerj.3020 -
An observational retrospective evaluation of 79 young men with long‐term adverse effects after use of finasteride against androgenetic alopecia
This study evaluates the long-term sexual and non-sexual side effects experienced by 79 young men after using finasteride for androgenetic alopecia, revealing a high prevalence of symptoms such as loss of penis sensitivity and decreased ejaculatory force.
DOI: 10.1111/andr.12147 -
Will Medical Management of Benign Prostatic Hyperplasia Result in Better or Worse Sexual Function in Men?
This mini-review evaluates how common medical treatments for benign prostatic hyperplasia (α-blockers and 5α-reductase inhibitors, alone or in combination) affect sexual function, summarizing risks of erectile and ejaculatory dysfunction as well as potential improvements from al…
DOI: 10.1016/s1879-5226(11)60003-1