Efficacy and tolerability of sildenafil/l-arginine combination relative to sildenafil alone in patients with organic erectile dysfunction

Andrology. 2020 Jan;8(1):143-147. doi: 10.1111/andr.12671. Epub 2019 Jul 2.


Background: Erectile dysfunction is defined as inability to achieve or maintain penile erection sufficient for sexual satisfaction. It is a serious problem that increases by age. The physiology of penile erection depends mainly on nitric oxide release.

Objectives: Compare the efficacy and safety of oral sildenafil 50 mg alone or in combination with l-arginine 3 g/day orally on the treatment of erectile dysfunction.

Material and methods: Randomized controlled study with two parallel groups of erectile dysfunction patients; One group received sildenafil 50 mg every other day, while the other group received a combination of sildenafil (every other day)/l-arginine on a daily base. Efficacy was assessed using International Index of Erectile Function-5 score at the baseline and after 8 weeks. Side effects were evaluated across the two groups.

Results: The mean age was 56.3 ± 5 and 56.2 ± 4.4 years in sildenafil and combination groups, respectively. International Index of Erectile Function-5 score was comparable between the two groups at the baseline (p value 0.44). International Index of Erectile Function-5 score was improved from 15.3 ± 2.5 at baseline to 19.2 ± 2.3 after treatment, and this was statistically significant with p value <0.0001. The score was slightly better in combination group in which the average International Index of Erectile Function-5 score was (19.8 ± 2.2) vs. (18.5 ± 2.3) in sildenafil group with p value 0.05. Side effects were more or less the same between the two groups except for gastritis which was more common on combination group.

Conclusion: Adding l-arginine to sildenafil demonstrated more efficacy than sildenafil alone for treatment of erectile dysfunction patients.

Keywords: erectile dysfunction; l-arginine; sildenafil.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Arginine / therapeutic use*
  • Drug Therapy, Combination
  • Erectile Dysfunction / drug therapy*
  • Humans
  • Male
  • Middle Aged
  • Phosphodiesterase 5 Inhibitors / therapeutic use*
  • Sildenafil Citrate / therapeutic use*
  • Treatment Outcome


  • Phosphodiesterase 5 Inhibitors
  • Arginine
  • Sildenafil Citrate