Take our Fertility Quiz and get 10% off!

Take our Fertility Quiz and get 10% off!

UTIs from sex? Here’s what’s happening in your body.

Written by:, PhD, Founder and Inventor of the Proov test — the first and only FDA-cleared test to confirm successful ovulation at home.


For those TTC, one thing is pretty likely — you are having a lot of sex. And unfortunately for many, that can mean an uptick in urinary tract health issues. In fact, urinary tract infections (UTIs) are the second most common infection and affect more than half of all women and are quite commonly derived from intercourse.

Especially for women TTC, you may be inclined to not go to the bathroom immediately after sex or are preoccupied with other tactics to conceive instead of taking the usual preventative measures to ward off a potential UTI (peeing, showering, cleaning with feminine hygiene wipes, etc.).

But UTIs from sex aren’t as simple as you might think. Why does sex lead to recurrent UTIs?

E coli is responsible for 80–90% of UTIs in the general population. Logically, you would assume that recurrent UTIs following sex are the result of new bacteria being repeatedly introduced into the urinary tract. However, in many cases, this is not what is happening.

Bacterial Biofilms:

Antibiotics don’t always clear an infection. Some bacteria can be left over. During an infection, bacteria can form biofilm on the bladder wall. Biofilm is a protective network of bacterial cells and secreted compounds that forms a shield that is difficult to penetrate. A tool implemented by bacteria in many infections (not just UTIs), biofilm can protect bacteria from the immune system and antibiotics, allowing them to stay dormant. Biofilms are difficult to detect and urine cultures may also come up negative. At a later time, these shielded bacteria can release themselves from the biofilm, replicate, and cause a “new” infection. This cycle can continue causing recurrent UTIs.

What seems like a separate UTI could actually be the same infection. Biofilms are now understood to play an important role in recurrent UTIs and may be why 26–44% of females with their first UTI will experience a second UTI within 6 months. But why (for many women) would these flare-ups continue to occur after sex if new E. coli isn’t being introduced? New research shows there may be an additional mechanism at work.

The Vaginal Microbiome

The vaginal microbiome is a complex community of microorganisms that live naturally in the human vagina and plays a role in recurrent UTIs. Healthy vaginal microbiomes are dominated by a genus of bacteria called lactobacillus. Lactobacilli excrete lactic acid and hydrogen peroxide that keep the normal vaginal pH low. A low pH limits the growth of potentially pathogenic bacteria that occur naturally in the vagina. Rising pH can allow for the overgrowth of the “bad” bacteria.

One of these types of bacteria is Gardnerella vaginalis, the bacteria primarily responsible for Bacterial Vaginosis (BV), a common infection in women. In fact the CDC estimates that 29.2% of all women ages 14–49 currently have BV yet 84% of those women do not experience symptoms. BV, however, can be a major risk factor for UTIs

“Studies examining the association between BV and UTI have found that women with BV have anywhere from a 2.2- to 13.7-fold increased risk of UTI depending on the population studied.”

Antibiotics taken for UTI treatment can actually disrupt the vaginal microbiome, causing pH to rise, increasing the risk of BV. This may be why it is common for women with recurring UTIs to also experience recurrent BV. These vaginal infections are now known to increase risk of more recurrent UTI episodes, causing a cycle of infections.

In order to appropriately address recurrent UTIs caused by sexual activity, one must prioritize the health of the vaginal microbiome.

What this means for women with recurring UTIs from sex

For women with recurring UTIs from sex, this could be the trigger that has been difficult to find. E. coli isn’t re-introduced; it is already there. A different bacterium, G. vaginalis, is transported to the urethra from the vagina during sexual activity where it damages the cells of the bladder wall, giving the biofilm-protected E. coli their opportunity to multiply and cause another infection. This is especially likely if a woman suffers from BV, which may be asymptomatic. This is because G. vaginalis is present at higher concentrations. It is important to note that G. vaginalis occurs naturally in the vagina potentially making these infections difficult to manage.

There are complex microbiomes at work in the female vagina, the skin of the sexual partner, and the urinary tract that are constantly changing and rebalancing. Research is still very early, though we do know that the vaginal microbiome is a key component to promoting urinary health.

About Uqora

Uqora creates innovative products for urinary tract health. Uqora was created by a chronic UTI sufferer (Jenna Ryan) and her biochemist partner (Spencer Gordon) who were both fed up with a heavy antibiotic rotation that acted as a band-aid for the underlying problem. This experience inspired Jenna and Spencer to start Uqora. Leveraging the best clinical research available, the couple began formulating effective urinary tract health products. Uqora takes an innovative approach to urinary tract health from multiple angles with three different products. (And no, we’re not talking cranberry.) 

Try Uqora with code PROOV20 for 20% off your first purchase at uqora.com.

Have questions? Email us!