Sildenafil does not improve sexual function in men without erectile dysfunction but does reduce the postorgasmic refractory time


Sildenafil is one of two oral drugs approved for first-line treatment of erectile dysfunction (ED). Anecdotally, some young healthy men who wish to enhance their sexual performance are requesting or abusing sildenafil. In this randomized double-blind, placebo-controlled clinical study, we investigated the effect of sildenafil in young men without ED. A total of 60 young healthy men age 20–40 y with no reported ED were enrolled for this single-dose home-use study. Subjects had used no medication in the 6 months prior to the study. All had been engaged in a stable relationship for at least 3 months. After completing the IIEF-5 questionnaire, patients were randomized in a double-blind fashion to receive either one 25 mg tablet of sildenafil (group 1) taken prior to intercourse, or an identical placebo tablet (group 2). All subjects completed a questionnaire relating to their erectile quality. There were no differences between the two groups in the reported improvement of erection quality, 12/30 sildenafil vs 10/30 placebo (Fisher's test, P=0.79). Sildenafil caused a significant reduction of the postejaculatory refractory time (12/30 vs 4/30) (χ2 test, P=0.04). Sildenafil does not improve erections in young healthy men. Sildenafil should not be given to young healthy men to improve their erections and patients should be advised against recreational abuse of the drug. In this limited single-dose home study, sildenafil appears to reduce the postorgasmic refractory time. Although controlled studies are needed to evaluate the efficacy of erection-enhancing drugs in premature ejaculation, it is possible that sildenafil might be useful for this indication.

Introduction and objectives

Sildenafil is a specific inhibitor of phosphodiesterase (PDE) type 5, and effective and well tolerated for erectile dysfunction (ED) of various etiologies.1,2,3

Since sildenafil has no effect on libido and since healthy young men usually have good-quality erections, there is no obvious reason to expect the drug to have a beneficial effect in young men without ED. However, due to media interest in the drug (often a so-called ‘lifestyle drug’), there seems to be a significant demand for sildenafil by young healthy males who wish to enhance sexual performance.4 Anecdotal reports of serious events have included young men abusing sildenafil in combination with other sex-related drugs such as amyl nitrate, or in combination with ecstasy or cannabis.5,6

The aim of our single-dose, home-use study was to investigate whether sildenafil improves erectile function in young healthy males.

Material and methods

In all, 92 young healthy men volunteers (age 20–40 y) were evaluated at the Department of Urology of Florence with the International Index for Erectile Function Questionnaire (IIEF-5).7,8 None reported ED, and only men whose IIEF-5 result in the range 26–30 (normal score) were eligible for our study.

No subjects had used any medication in the 6-month period prior to the study. All had been engaged in a stable relationship for at least 3 months. A physical examination was performed on every subject with particular emphasis on the genitourinary system to reveal unsuspected findings such as Peyronie's disease and hypogonadism. Any subjects with possible risk factors associated with the use of sildenafil were excluded. According to these inclusion criteria, 60 men were finally included in this study.

All patients signed an informed consent form explaining the nature of the study, which had been previously approved by the Ethics Committee of our Institution. They were sequentially randomized to one of the following groups. Group 1 (30 subjects, mean age 33 y; range 21–37) was prescribed one tablet of sildenafil of 25 mg and group 2 (30 subjects, mean age 31 y; range 22–39) a placebo tablet. The two groups were similar for age, physical characteristics and IIEF-5. In both cases, the sildenafil and the placebo tablet were placed in an opaque gelatin capsule to be taken 1 h before sexual intercourse. All the subjects filled a questionnaire with questions about sexual performance, side effects, and their intention to make use of the medication again (see Appendix A).

Refractory time was recorded by subjects measuring their time to have a second erection (with sexual stimulation) one 1 day without taking the sildenafil or placebo capsule, and then on another day after taking the capsule.

Statistical analysis was performed by Fisher's exact test and χ2 test. The test were considered significant at a level of P<0.05.


There were no differences between the two groups in the improvement of erectile quality 12/30 (40%) sildenafil vs 10/30 (33.3%) placebo (Fisher's test, P=0.79) (Figure 1). There were no significant differences in the following reported aspects of sexual performance compared to using viagra or placebo (Table 1).

Figure 1

Do you think that your sexual performance after the drug has been improved by the drug?

Table 1 What aspects of your sexual performance you believe has improved?

In all, 12 (40%) men in the sildenafil group reported a noticeable reduction of the postejaculatory refractory time compared to only four (13.3%) in the placebo group (χ2 test, P=0.04; Table 1).

In the sildenafil group, the median refractory time was 14.9 min before taking the treatment and 5.5 after with a reduction of 9.4 min. For placebo group, the median time was 13.8 before and 12.4 after, with a difference of 1.4, a clinically significant difference.

Side effects were more frequent in the sildenafil group 5/30 (16.6%) (two headache; three flushing) vs 1/30 (3.3%) using placebo (headache), but this did not achieve significance in the numbers studied here (Fisher's test, P=0.195).

With regard to future intentions only a few subjects would take the study drug again and there was no significant difference between the two groups 2/30 (6.6%) sildenafil vs 4/30 (13.3%) placebo (Fisher's test P=0.671).

Discussion and conclusions

In this parallel, double-blind study erections were improved in 40% of patients by sildenafil and in 33% by placebo, respectively. There were no statistical differences between the two groups.

These data suggest a strong placebo effect in these young men. This is an important data and parallels the high percentage of success of placebo in andrological patients with psychogenic ED.

Although we had hoped to have carried out a crossover study, and to assess others doses, the local Ethics Committee specified a single dose of 25 mg with no crossover. Dundar recently reported a study on side effects of sildenafil vs placebo in a group of young healthy volunteers using a tablet of 50 mg. The most common side effects, mirroring clinical practice, were flushing, headache, dyspepsia and palpitation (all side effects were reported as mild).9 These data were confirmed also by Aversa et al10 in a study using 100 mg.

In conclusion, we can state that 25 mg of sildenafil citrate given as a single dose to young healthy men does not improve erections. These data suggest that sildenafil must not be given to young healthy men to improve their erections. Urologists can confidently inform healthy young men asking for the drug that they will not benefit from it. This may reduce the risks of casual usage in association with drugs like ecstasy or amyl nitrate, with the attendant dangers.

The reduction of the postejaculatory refractory time, also reported by Aversa et al10 in a study on seminal parameters in normal males, made us consider whether there may be a place for the use of sildenafil in some men with premature ejaculation, although this study was not designed to address this issue.

Premature ejaculation, the inability to delay orgasm for an acceptable length of time, is the most common presentation of ejaculatory dysfunction. It may present on its own or with other manifestations of ED. There is currently no effective therapy for this condition, although it has been treated with various psychosexual techniques including the Seman's maneuvre or Masters and Johnson's squeeze technique. Although these work well for some patients in the short term, convincing long-term treatment outcome data are lacking. Moreover, many men decline psychosexual counselling for a variety of reasons and optimal results are highly dependent on the participation of the sexual partner in the counselling sessions. Furthermore, there is little evidence for the effectiveness of psychosexual techniques in men who suffer from precocious ejaculation (ie anteportal ejaculation) or in men who suffer from premature ejaculation linked to difficulty in obtaining or maintaining an erection.

Topical applications may be used. Oral pharmacotherapy such as the tricyclic antidepressants and selective serotonin reuptake inhibitors are associated with variable rates of success when taken daily or as needed. These drugs act by increasing of the ejaculatory latency time;11 however, they have some, albeit minor, side effects in men who are not suffering from clinical depression.

It has been suggested that young men with a short refractory time may experience more controlled ejaculation during subsequent coitus.11 Some uroandrologists recommend intracavernosal vasoactive drugs, that result in a continued erection after ejaculation and many improve the sexual experience for the partner,12 so that even if the patient ejaculates too soon he can still maintain an erection. From our data, it might be suggested that sildenafil could be used as a less invasive method of administering such treatment, and that a study to evaluate the place of this drug in premature ejaculation is justified. Interestingly, since this study was carried out, three papers have suggested that PDE5 inhibitors may have such a role.13,14,15

However, we stress again that sildenafil has no place in improving normal erections. We think it unlikely that many authorities would consider its use ethical in healthy men who simply wish to reduce their latency time.


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We thank Dr Eugenio Marro for Statistical analysis.

Author information

Correspondence to N Mondaini.

Appendix A: Questionnarie

Appendix A: Questionnarie

Do you think that your sexual performance after the drug has been better? (YES/NO)

What aspects of your sexual performance do you believe improved?

  1. a)

    Easier erection?

  2. b)

    Erection more rigid?

  3. c)

    Erection lasted longer?

  4. d)

    More intense orgasm?

  5. e)

    A reduction of your *post-ejaculatory refractory time?

Did you have any side effects?

Would you take the drug again?

(*Refractory POST-EJACULATORY TIME: time to get another erection following ejaculation.)

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Mondaini, N., Ponchietti, R., Muir, G. et al. Sildenafil does not improve sexual function in men without erectile dysfunction but does reduce the postorgasmic refractory time. Int J Impot Res 15, 225–228 (2003).

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  • sildenafil
  • premature ejaculation
  • refractory time
  • IIEF
  • drug abuse

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