Every time you have sex, it’s actually an orgy. 

Let us explain: Being in a sexual relationship with another person means sharing touches, bodily fluids—and microbes. Every time you pursue pleasure with a partner(s), trillions of microscopic players also get in on the action, from the diverse bacteria strains of the saliva to the protective communities of the skin microbiome.

Caring for these invisible landscapes can help enhance your pleasure and that of your partner, all while supporting the overall health of everyone involved. Read on to explore a few of the friskiest microbial communities across your body and their role in sexual health.

The Oral Microbiome: Every Kiss Begins With Microbes

The oral microbiome (consisting of the gum crevices, tongue, hard palate, soft palate, cheeks, and lips) is the runner-up for the largest and most diverse microbiota in your body—second only to your gut.¹ Your mouth is home to billions of bacteria and fungi, influencing everything from bad breath (mood killer) to heart disease, and more.^1,2 And since there are so many different (and wonderful) ways to use your mouth during sex, it’s no surprise that the oral microbiome plays a major role in sexual health as well.

In one study published last year in Nature, researchers analyzed saliva samples from thousands of people across 20 countries and found that those who lived together shared 10 times more similar oral bacteria strains than those who did not. This effect was even more pronounced among romantic couples, who shared more oral bacteria species than other cohabitants.³ 

So how does bacteria migrate from one mouth to another? Kissing presents a major opportunity: One fascinating older study asked couples (both hetero- and homosexual) to provide saliva samples and answer questions on how often they smooched per day. Besides finding that men in heterosexual couples tended to over-report how much they kissed compared to their female partners (classic), researchers found that those who shared at least nine kisses daily tended to have the most similar oral microbiome makeup.⁴ 

Some bacteria shared between partners seem to only stay in the saliva temporarily, while others stay on the tongue for a long time and find a suitable place to colonize—which really gives new meaning to “swapping spit.”

How to Care for the Oral Microbiome 

All this sharing means that taking care of your own oral microbiome through habits such as maintaining good oral hygiene by brushing and flossing regularly, quitting smoking, and reducing sugar intake can also indirectly pay off for your partner.^5-7 

Other ways to protect this pleasure center? While it’s tempting to do a quick swish before a makeout session, antibacterial mouthwash is actually detrimental to the oral microbiome. A 2020 study showed that healthy people who used chlorhexidine (an antiseptic) mouthwash experienced a shift in their salivary microbiomes, so stick with products that are free of harsh disinfectants when you can.⁸ 

The Skin Microbiome: I Wanna Hold Your Hand 

The skin is the largest organ in the body, acting as a physical barrier to the outside world.⁹ It provides plenty of surface area for microbial communities to set up shop and protect against pathogens, assist with wound healing, and even help direct the immune system.¹⁰ 

Just as each area of your body plays a different role during sex, each individual microbial community on your skin has a slightly different purpose and function.

Take the breast microbiome—which is teeming with relatively rare bacteria not often found on other body parts.¹¹ This microbiome likely supports breast health by stimulating resident immune cells.¹² Areolar skin also has its own distinct bacterial community, which contributes to developing the infant microbiome and immune system during breastfeeding.¹³

And, as you use your fingers in all sorts of ways during sexual activity, know that you’re also engaging a completely different (and ever-shifting) ecosystem: The microbiome of the hands is constantly changing every time you pick up and spread microorganisms through contact with people, objects, and your surroundings.¹⁴ 

When the skin is engaged through intimate physical touch, a cascade of the feel-good oxytocin hormone soon follows, making the skin microbiome a living shield and arousal center.

How to Care for the Skin Microbiome 

Our fingertips and faces tend to be the most receptive to physical touch, but everyone will have their own pleasure centers on the skin.¹⁵ Traversing new areas to touch, kiss, and caress can be a steamy way to get to know your partner (and their microbial zones) during sex. 

Washing up before and after this exploration can help strengthen your personal skin microbiome. However, there’s no need to go overboard, as studies have shown that the use of antibacterial soaps can have potentially negative effects on the skin barrier.¹⁶ If you’re freshening up before sex, stick with good-old soap and water. We recommend washing your hands after sex, too, to avoid spreading genital microbes to other areas of the body. 

The Vaginal Microbiome: A Microbial Miracle

The vaginal microbiome (VMB) is unique, fascinating, and beautiful—much like the vagina itself.

When stable, the VMB is dominated by the bacterial genus Lactobacillus, which produces lactic acid to maintain a moderately acidic environment. But the bacteria, fungi, and other microscopic organisms of the vagina are extremely sensitive to disruptions. Everything from cleansers to menstruation, exercise to antibiotics, can damage these protective bacteria and elevate pH levels, leading to a host of issues, including increased risks of STIs, pelvic infections, and bacterial vaginosis (BV).^17-22

Establishing a strong, resilient vaginal microbiome can help defend against the most prevalent women’s health issues of today. From vaginal microbiome transplants for tackling chronic BV to bacterially informed treatments for cervical cancer, the research in this space has groundbreaking potential.

Sex, obviously, plays a major role in the composition of the vaginal microbiome—and it can act as a disrupter. Women who have sex with men can experience shifts in vaginal composition following penetration (more on this up next!).²³ This is also true for women who have sex with women, as vulva-to-vulva contact can create a natural vaginal microbiome transplant. In this case, studies have shown that if your partner’s microbiome is strong and protective (dominated by lactobacilli, with a low microbial diversity), you are also more likely to have a stable microbiome that is resistant to infections such as BV.²⁴ 

How to Care for the Vaginal Microbiome 

Because the vaginal microbiome is so sensitive to disruption, it’s vital to take additional care when introducing anything new to it—be it a toy, body part, or lubricant. Many commercially available lubes are hyperosmotic, meaning they drain and dehydrate moisture from cells, potentially causing vaginal tissue to shrink or thin and putting you at risk of abrasions.²⁵ Additionally, pre-clinical research has found that lube containing an ingredient called chlorhexidine gluconate potentially harms the vaginal microbiome by reducing the growth of Lactobacillus species.²⁶ Taking the extra time to seek out a microbiome-friendly lube can protect this delicate community and lead to more pleasure in the long run. 

Similarly, caring for sex toys by washing with soap and water between uses and between partners can keep your microbial partners healthy. One study found that sharing sex toys with female partners was associated with a reduced concentration of lactobacilli.²⁷ Penetrating the vagina with fingers and sex toys was also associated with increased colonization of Gardnerella vaginalis (a species of bacteria that can cause BV).

The Penile Microbiome: The Next Frontier in Sexual Health

There are a few elements of the penile microbiome—and they all seem to shift during sex. The makeup of the mucosa (skin) of the penis is influenced by sexual partners, as well as neighboring microbial niches (think: the skin, gut, and even urine).²⁸ Sperm and the male urethra—the canal that runs through the penis and carries urine and sperm—also have microbiomes that can be reshaped by vaginal sex.^29,30 

Researchers are just beginning to look at what these ever-shifting landscapes mean for our health, but they seem to play a role in reproduction and fertility. Penile microbiomes can harbor biofilms containing pathogenic bacteria like Gardnerella, which can be passed on to partners during unprotected sex.³¹ Men with seminal (sperm) microbiomes high in the bacteria Lactobacillus gasseri also seem to be more likely to have fertility challenges, leading researchers to propose that a “microbiological homeostasis” could be the ticket to establishing pregnancy.³²

Overall, though, research on this microbial world is quite new, and plenty of questions—such as how the penis microbiome might have protective effects on vaginal health, how it changes during sex with male partners, and how it responds to lubrication—remain, just waiting to be answered under the sheets. 

How to Care for the Penile Microbiome

Again, there isn’t much established research on the penile microbiome or its role in a healthy sex life. But it stands to reason that as with the vaginal microbiome, avoiding harsh antibiotic cleaners before and after sex (and really, always) is a good move in this region. Using condoms with new partners can also help shield from any potentially disruptive bacterial back-and-forth. 

The Gut Microbiome: An Unexpected Third Wheel

The most well-known (and well-studied) microbiome in and out of the bedroom, your gut microbiome is home to trillions of bacteria. You may know it for its role in strengthening your gut barrier, maintaining an acidic environment to dissuade pathogens, helping break down food, and stimulating digestion—but it also influences romance and intimacy.³³ 

Gut microbes help to get you “in the mood” by regulating emotions and behaviors along the gut-brain axis—the neural pathway by which your gut microbes communicate with your nervous system. 

New research suggests that the gut microbiome might also influence the vaginal and penile microbiomes. 

While the vagina is (obviously) not a part of the gastrointestinal tract, the proximity of the vaginal opening to the rectum makes some crossover inevitable: Microbes in the vagina can make their way to the gut, and vice versa, along the essential superhighway known as the gut-vagina axis. 

The gut-vagina axis also seems to play a role in regulating estrogen, a hormone that relates to sexual desire.³⁴ There’s a subset of microbes residing in your gut, known as the estrobolome, that can impact the amount of estrogen circulating in the body. Your estrogen levels affect the overall health, thickness, and mucus production of the vaginal lining, creating natural lubrication—which we all know can meaningfully impact sexual pleasure.³⁵ Estrogen generally correlates to an increase in sex drive, whereas too little (or, conversely, too much) can lead to low sexual desire, depression, and anxiety.³⁵ 

There is also mounting evidence for a gut-testis axis that influences sperm health and sexual function.³⁶ When in a strong, protective state, the gut microbiome maintains a symbiotic, mutually beneficial relationship with the testes. Disruption of the gut microbiome, however, can cause inflammation throughout the body—including in the testes. As such, studies have shown that gut dysbiosis is linked to lower sperm quality and quantity.³⁷ 

How to Care for the Gut Microbiome 

Thankfully, your gut microbiome benefits from all the same things you do—in other words, the healthy habits that support your whole body also support your microbial (and sexual) partners. From eating a high-fiber, mostly plant-based diet to reducing stress, getting good quality sleep to developing a healthy, pleasure-based relationship to your sexuality, there are simple, actionable ways to support your gut on the daily.^38,39 

A Happy Ending

Sex can be complicated, but it can (and should!) also be fun, liberating, experimental, and joyful. Thinking about how to involve and care for all parts of your body, including your microbes, is just another way to engage your senses, enrich your experience, and make sure everyone (yes, even your bacteria) has a happy ending.