A reader asked the following question:

“Is it true that peeing right after sex can stop you from getting a UTI?”

Thanks for this great question. Let’s take a look at what the research says. Before we do, let me first mention that it is pretty well established that urinary tract infections (UTIs) can be caused by sexual activity; however, this appears to be something that happens to women more often than men [1].

With that said, because sex creates a unique opportunity for bacteria to enter the urethra, it would only seem intuitive that post-sex urination would reduce the odds of developing a UTI--after all, urine could potentially flush bacteria out before an infection sets in, right? However, research linking post-sex urination (known scientifically as “postcoital voiding”) to UTI risk has produced mixed results.

For instance, a 1996 longitudinal study of 819 women aged 18-40 found that urinating within an hour after sex was not a statistically significant predictor of UTI risk; however, use of a diaphragm with spermicide was related to increased risk [2].

Likewise, a 2000 study comparing 229 women with UTIs to 253 randomly selected women with no history of UTIs found no link between post-sex urination patterns and UTI risk; again, though, women who used spermicides were at higher risk [3]. The thought here is basically that spermicides increase the rate of colonization of certain bacteria and that this increases UTI risk. It’s also worth mentioning that this particular study found that increased infection risk was related to having had one’s first UTI at a young age (<15) and having a mother with a history of UTIs. Both of these associations suggest that--regardless of sexual behavior--some women simply seem more predisposed to developing UTIs than others.

That said, a few studies have found links between delayed urination after sex and increased risk of UTIs; however, most of these are older studies (1990 and earlier, they were based on small samples, and they were not longitudinal in nature, such as this 1979 study of 84 female college students. That said, I did come across two recent studies finding that urinating soon after sex was linked to lower STI risk: one was based on a small sample of pregnant women in Iran, and the other based on a small sample of pregnant women in Saudi Arabia.

Taken together, it's hard to know what to make of this conflicting body of research. As such, I reached out to Dr. Debby Herbenick, Director of the Center for Sexual Health Promotion at Indiana University. She noted that the research in this area is "extremely limited" and that research conducted in the last few years on the bacterial environment of the urethra "calls into question what we really know/think we know about UTIs and their influences, including sexual influences.

Dr. Herbenick said that her personal take on the issue is that "if someone wants to do it - it can't hurt and might help, but we can't say for sure." She also recommends that if you're someone who seems to get recurrent UTIs that it's probably worth seeing a specialist rather than your regular doctor.

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[1] Eke, N. (2002). Urological complications of coitus. BJU International, 89(3), 273-277.

[2] Hooton, T. M., Scholes, D., Hughes, J. P., Winter, C., Roberts, P. L., Stapleton, A. E., ... & Stamm, W. E. (1996). A prospective study of risk factors for symptomatic urinary tract infection in young women. New England Journal of Medicine, 335(7), 468-474.

[3]Scholes, D., Hooton, T. M., Roberts, P. L., Stapleton, A. E., Gupta, K., & Stamm, W. E. (2000). Risk factors for recurrent urinary tract infection in young women. Journal of Infectious Diseases, 182(4), 1177-1182.

Image Source: 123RF.com/chrupka

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