Why You Seem to Get an Infection Every Time You Have Sex

If you’re a person with a vagina, you know the drill: pee after sex or bear the consequences. Much like other scraps of slumber party wisdom—don’t sit too long in a wet swimsuit, always keep cranberry juice in the fridge—this gospel is the first line of defense against the host of painful and frustrating infections that seem to be just part and parcel of having a vagina.

Yet even if you follow the “rules,” it’s difficult to avoid becoming one of the millions of Americans who visit the doctor each year for vaginal inflammation and infection.¹ And, concerningly, the medical treatments that do exist for these varied gynecological complaints are often mere bandaids, rarely addressing the root cause of the issue and contributing to vicious recurrences. 

So much of our inability to prevent and effectively treat gynecological pain and infection comes down to the relentless gap in scientific and medical research into so-called “women’s issues.” Until this is addressed, however, there are ways to be a more educated and empowered steward of your body during sex—and many of them come down to understanding your vaginal microbiome.

Science with us—nerdy reads for your inbox biome¹

Sign Up

¹By signing up, you consent to receive Seed emails.

The Vaginal Microbiome (VMB): A Silent Sidekick in Sexual Health and Satisfaction

While you may be familiar with your gut microbiome, your body actually hosts multiple microbial ecosystems—including one in the vagina. The billions of microorganisms housed in your vagina comprise a dynamic ecosystem known as the vaginal microbiome (VMB).^2,3

The VMB is adaptive, evolving, and—crucially—underexplored. Like so much of vaginal health, the VMB has only recently been subject to study—and what we’re discovering points to its vital role in protecting reproductive health, preventing pathogenic growth, and reducing inflammation in the vagina.^4,5,6 

While your gut microbiome thrives on a diversity of bacterial species, the vaginal microbiome functions best when one particular genus of bacteria is predominant: Lactobacillus. The lactobacilli in your VMB play a key role in keeping your vagina clean, fighting off infections, assisting in pregnancy, and possibly defending against gynecological cancers.^7,8 And the importance of maintaining stability among this community of microbes cannot be overstated.

Infections Associated With the VMB

Here are a few infections that seem to arise when there is an imbalance, or dysbiosis, of the vaginal ecosystem: 

Bacterial vaginosis (BV): Bacterial vaginosis affects nearly one-third of reproductive-aged women at any given time, and is characterized by changes in vaginal odor, abnormal discharge, and discomfort. Individuals experiencing BV have an imbalance of the vaginal microbiome where beneficial bacteria are outnumbered by pathogens. While some BV infections may be asymptomatic, others can be debilitating, limiting your ability to enjoy sex and resulting in shame or confusion. When left untreated, BV can also increase one’s risk of STIs, HIV, pelvic inflammatory disease, and infertility.^9,10 

Most BV is treated with antibiotics, which, while effective, rarely eliminate the problem entirely: Up to 69% of people treated for BV will have a recurring infection within 12 months (and ~50% within 6 months).¹¹ Additionally, antibiotics work by killing bacteria, and cannot fully distinguish between “good” and “bad” bacteria—so even if they succeed in reducing the pathogenic load, they also disrupt the microbiome in ways we are only beginning to understand.¹² 

Yeast infections: Yeast infections are also the result of a disruption to the vaginal microbiome—often due to hormonal changes, sexual activity, excessive cleaning (like douching), or, paradoxically, antibiotics taken for BV or another infection, which allows vaginal yeasts to grow in excess and changes the optimal pH of the vagina.^12,13 An estimated 75% of women will experience a yeast infection during their lifetime, and most of these will be treated with an antifungal medication.¹⁴ While effective, these do not totally prevent recurrent infection either: Up to 9% of women suffer from 3-4 or more yeast infection episodes per year.¹⁴ 

Urinary tract infections (UTIs): UTIs can feel like a rite of passage in the life of anyone with a vagina and an active sex life, affecting 50-60% of adult women over the course of their lives.^15,16 Dysbiosis of the VMB has been shown to be a key factor in susceptibility to UTIs.¹⁶ Multiple studies have shown that E. coli—the primary UTI-causing pathogen—is more common in women whose vaginal microbiomes show low levels of protective Lactobacillus species.¹⁶ During sex, bacteria from the vagina are relocated to the urethra. If that bacteria is pathogenic, rather than harmless, a UTI can occur. Similar to BV, UTIs are treated by a course of antibiotics, and, again, have a relatively high recurrence rate of 30-50%.¹⁷

These gynecological infections can make daily life uncomfortable, cause embarrassment or shame, and prevent you from participating in and enjoying sexual activity. The frequency with which most people experience them can make it seem as though they’re just part of the “burden” of having a vagina, especially if you’re sexually active—but thankfully, that doesn’t need to be the case.

How to Have Sex That‘s Good for You and Your Microbiome 

Multiple studies have confirmed a link between sexual activity and disruptions to the vaginal microbiome that can cause the infections above.¹⁸ On a purely mechanical level, this makes sense: introducing any “foreign” object to the vagina also introduces “foreign” microbes—in other words, microbes other than the protective Lactobacillus species your vagina needs for optimal functioning. 

That doesn’t, however, mean sex—penetrative or not, with a partner(s) or not—should be avoided. Here are a few ways to protect yourself while still experiencing (and prioritizing!) pleasure: 

1. Maintain optimal pH

The lactobacilli in your VMB produce lactic acid as a byproduct of fermentation and keep the pH of your vagina moderately low.¹² Semen is more alkaline than the environment of the vagina, and studies show that condomless sex can increase the number of anaerobic bugs in the vaginal flora, leading to higher rates of BV.^12,19 Similarly, the use of toys without proper cleaning or lubrication can also increase the pH of the vagina.²⁰ Using condoms (especially with new partners), applying a microbiome-friendly lube, and regularly cleaning sex toys can help mitigate these changes, as can taking a vaginal probiotic.²¹

2. Use care with new partners

While BV is not considered an STI, studies have shown a correlation between new or multiple partners and incidents of BV.²² 

Some research suggests that men can carry BV-associated bacteria on their penises. These bacteria form biofilms (protective layers) making them tough to get rid of. Men might pass these BV-associated bacteria or their biofilm-forming ability to their female partners during unprotected sex, despite not being able to catch it (ugh).²³ 

Engaging in oral sex with new partners can also increase your risk of BV, as one of the bacteria found in the oral microbiome, Fusobacterium nucleatum, is linked to vaginal dysbiosis.²⁴ Doctors recommend using barrier methods when possible.

3. Practice good hygiene

And no, we don’t mean douching. While it may not exactly be conducive to steamy, spontaneous sex, the gold standard for preventing vaginal dysbiosis is to use a gentle cleanser to clean your hands, toys, and the surface of your genitals prior to sexual activity to prevent the introduction of foreign pathogens that cause UTIs and other vaginal infections.

4. Use lubrication

Even gentle sexual activity can lead to microscopic abrasions in the vagina, all of which can be entry points for pathogenic bacteria. Using proper lubrication can mitigate the potential for irritation and—bonus!—lead to more pleasure during sex. Look for a lube that is free of synthetic fragrances or other pH disruptors to protect your VMB. 

An Educated, Empowered Approach to Sex

While it can be frustrating, as a person with a vagina, to feel that so much of sex is fraught and potentially harmful, an educated approach to sex is an empowered one. Understanding the intricacies of your body and becoming more medically literate can ultimately lead to a better, less painful, more freeing relationship with your own sexuality—one that benefits you and the millions of protective bacteria in your vaginal microbiome.