5-alpha reductase inhibitors and erectile dysfunction: the connection

J Sex Med. 2008 Dec;5(12):2917-24. doi: 10.1111/j.1743-6109.2008.01001.x.


Introduction: Benign prostatic hyperplasia (BPH) is a common problem affecting middle-aged and elderly men. First-line medical therapy includes alpha 1blockers and 5alpha-reductase inhibitors (5ARIs), such as finasteride and dutasteride. 5ARI use has been associated with adverse sexual outcomes, including erectile dysfunction (ED), ejaculatory dysfunction (EjD), and decreased libido.

Aim: To clarify the association between sexual adverse effects (AEs) and 5ARIs through review of literature concerning 5ARIs and to review the proposed mechanisms of these effects.

Methods: A comprehensive literature review, using MEDLINE and PUBMED search engines, was conducted for all publications concerning 5ARIs and sexual AEs.

Main outcome measure: Sexual adverse effects, such as ED, EjD, and decreased libido, were the measured outcomes of this literature review.

Results: Sexual AEs are reported in clinical trials at rates of 2.1% to 38%. The most common sexual AE is ED, followed by EjD and decreased libido. These effects occur early in therapy and attenuate over time. A proposed mechanism for sexual dysfunction involves decreased nitric oxide synthase activity due to decreased dihydrotestosterone.

Conclusions: The connection between 5ARIs and sexual dysfunction is apparent upon review of the literature. Though theories have been proposed, little is known about the exact mechanisms behind 5ARI-related sexual dysfunction. Since the connection between 5ARIs and sexual AEs is established in the literature, future research should be directed toward deciphering the pathophysiologic mechanisms. When more basic science knowledge is attained in this area, the focus can shift toward prevention and treatment.

Publication types

  • Review

MeSH terms

  • 5-alpha Reductase Inhibitors*
  • Adrenergic alpha-Antagonists / adverse effects
  • Adrenergic alpha-Antagonists / therapeutic use
  • Azasteroids / adverse effects
  • Azasteroids / therapeutic use
  • Drug Therapy, Combination
  • Dutasteride
  • Ejaculation / drug effects
  • Erectile Dysfunction / chemically induced*
  • Finasteride / adverse effects
  • Finasteride / therapeutic use
  • Humans
  • Libido / drug effects
  • Male
  • Prostatic Hyperplasia / drug therapy*


  • 5-alpha Reductase Inhibitors
  • Adrenergic alpha-Antagonists
  • Azasteroids
  • Finasteride
  • Dutasteride