Do food and dose timing affect the efficacy of sildenafil? A randomized placebo-controlled study

J Sex Med. 2007 Jan;4(1):137-144. doi: 10.1111/j.1743-6109.2006.00400.x.


Introduction: Sildenafil citrate has been used worldwide by men with erectile dysfunction. The prescribing information for sildenafil suggests ingestion 1 hour before sexual activity and also notes reduced maximum plasma concentration and delayed time to maximum concentration following ingestion with a high-fat meal. The clinical impact of coingestion of food and these factors has never been evaluated.

Aim: To determine, using a naturalistic study design, whether sildenafil taken 1 hour before or during a meal compared with usual ingestion 30-60 minutes before sexual activity affects efficacy or patient satisfaction.

Methods: After a 1-2-week washout, 48 men (29-79 years old), currently satisfied with sildenafil, followed each of four regimens: (A) sildenafil 1 hour before a meal and placebo 30-60 minutes before planned coitus vs. (B) placebo 1 hour before a meal and sildenafil 30-60 minutes before coitus; and (C) sildenafil during a meal and placebo 30-60 minutes before coitus vs. (D) placebo during a meal and sildenafil 30-60 minutes before coitus. Subjects were not instructed to change their regular dietary habits during the course of the study.

Main outcome measures: Change from baseline in the International Index of Erectile Function (IIEF) Erectile Function (EF) domain score, responses to Sexual Encounter Profile (SEP) questions 2 (erection sufficient for penetration) and 3 (erection sufficient to complete intercourse), and measures of patient preference and satisfaction.

Results: Mean changes in IIEF-EF domain scores were 11.4 for regimens A and B and 11.2 for C and D. Positive SEP2 responses were recorded for 93.9% and 91.8% of intercourse attempts in A and B and 91.4% and 92.6% in C and D. Corresponding results for SEP3 were 84.7% and 85.9%, and 83.4% and 87.5%, respectively. There were no significant differences between pairs of treatments on satisfaction. The time between sildenafil ingestion and intercourse attempt (0-0.5 to >10 hours) had no significant effect on responses to SEP2, but decreased responses to SEP3 from a maximum of 92.8% at 1.5-2 hours to 81.6% at more than 10 hours (P = 0.003).

Conclusions: No significant loss of efficacy occurs when sildenafil is taken shortly before or with a meal. The duration of action for sildenafil may exceed 10 hours.

Publication types

  • Controlled Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Erectile Dysfunction / drug therapy*
  • Food-Drug Interactions*
  • Humans
  • Male
  • Middle Aged
  • Patient Satisfaction
  • Penile Erection / drug effects
  • Phosphodiesterase Inhibitors / administration & dosage*
  • Piperazines / administration & dosage*
  • Purines / administration & dosage
  • Sildenafil Citrate
  • Sulfones / administration & dosage*
  • Treatment Outcome
  • Vasodilator Agents / administration & dosage*


  • Phosphodiesterase Inhibitors
  • Piperazines
  • Purines
  • Sulfones
  • Vasodilator Agents
  • Sildenafil Citrate