Viagra users may experience more condom failure

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Men who use Viagra and other erectile dysfunction drugs are four times more likely to experience condom breakage than other men, report American researchers in the September issue of Sexually Transmitted Infections. However a separate study conducted by the same team did not find the same association, which would need to be confirmed by other research.

In the first study, the researchers used newspaper and internet advertisements to recruit a convenience sample of 440 men who used condoms for vaginal sex. The self-completion questionnaire focused on the most recent occasion they had sex.

Just under one in ten of the men had used an erectile dysfunction drug on that occasion. For 12% of these men the condom broke, compared to 5% of men who didn’t use an erectile dysfunction drug.

Glossary

multivariate analysis

An extension of multivariable analysis that is used to model two or more outcomes at the same time.

sample

Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

odds ratio (OR)

Comparing one group with another, expresses differences in the odds of something happening. An odds ratio above 1 means something is more likely to happen in the group of interest; an odds ratio below 1 means it is less likely to happen. Similar to ‘relative risk’. 

exclusion criteria

Defines who cannot take part in a research study. Eligibility criteria may include disease type and stage, other medical conditions, previous treatment history, age, and gender. For example, many trials exclude women who are pregnant, to avoid any possible danger to a baby, or people who are taking a drug that might interact with the treatment being studied.

adjusted odds ratio (AOR)

Comparing one group with another, expresses differences in the odds of something happening. An odds ratio above 1 means something is more likely to happen in the group of interest; an odds ratio below 1 means it is less likely to happen. Similar to ‘relative risk’. 

Men reporting a longer duration of intercourse were also more likely to report condom breakage. However, in multivariate analysis, which controls for the skewing effect of other factors, erectile dysfunction drug use remained significant - users were four times more likely to report condom breakage (adjusted odds ratio 4.04, 95% confidence interval 1.06 - 15.41).

The researchers suggest that as Viagra and related drugs increase swelling during an erection, it is plausible that condoms become more tight-fitting. They say that users of these drugs may need to be advised to use condoms that are large enough for an enhanced erection. Moreover, users should be made aware that having sex for longer is associated with condom breakage.

However the same team of researchers published a separate study earlier this year in the Journal of Sexual Medicine, which did not find the same association.

In this study, a different group of 705 men were recruited via a website selling sexual paraphernalia. Although most men were heterosexual, some were reporting on anal sex. Men who used recreational drugs were excluded.

Once again, the men were asked about the last time they used a condom for penetrative sex. Seven per cent of men reported using an erectile dysfunction drug.

Condom breakage was rarely reported in this sample, and was no more commonly reported by erectile dysfunction drug users.

On the other hand, users were actually more likely to report the condom slipping off or erection problems during sex. The researchers concluded from this that while Viagra and similar drugs may improve men’s erections, they do not always eliminate all erection problems, especially those associated with condom use.

The researchers believe that their studies highlight the importance of further research into the implications of using erectile dysfunction drugs.

References

Crosby R et al. Is phosphodiesterase type 5 inhibitor use associated with condom breakage? Sex Transm Infect 85:404-405, 2009.

Sanders SA et al. Do phosphodiesterase type 5 inhibitors protect against condom-associated erection loss and condom slippage? J Sex Med 6:1451-1456, 2009.