The Grossest Things Kissing Does To Your Body

Kissing is one of the best parts about being human. While other animals kiss in their own way, they don’t do it quite like us: lips slightly parted, heads tilted to one side, and a dance of tongues that can go from subtle and flirtatious to deeply passionate in a matter of seconds. It’s simply wonderful. And when you find that person who kisses the same way you do — because we all have a bit of a different kissing technique — it feels like magic has just exploded across your lips, and you can feel the tingling from head to toe.

But as much as kissing can be an amazing experience, it’s also pretty darn gross. According to a 2014 study published in Microbiome, all it takes is one 10-second kiss to transfer 80 million bacteria between the two mouths that are locking lips. Yes, you read that correctly: 80 million. That’s a lot of bacteria for one kiss — now think about what’s going on with a hot and heavy make-out session that lasts an hour or more. Yikes. And, of course, if one partner has a cold sore, or a virus of any kind, you better believe that’s being shared too.

However, those are just the most obvious unpleasant things that can happen when you kiss someone. In fact, all those kisses you’ve had and will continue to have are affecting your body in ways you couldn’t have conceived, like disrupting gut health and messing with your dental hygiene.

If you’ve ever kissed someone and found yourself feeling ill afterward, you’re certainly not alone. The bacteria that are being transferred aren’t merely swirling around in your mouth. Instead, the saliva from both you and your partner is being ingested. Not the most lovely thought you want to have in your head when you’re kissing someone, but it’s true.

“Mouths can serve as a transmission route for germs because there is close connection with the gastrointestinal and respiratory systems, and these are common sites of infections for germs,” microbiologist Kelly Reynolds, Ph.D., told Cosmopolitan. Because of this, your gut microbiome can be altered — sometimes in a way that can make you feel a little sick and sometimes in a way that’s actually good for you. 

According to a 2021 study published in Frontiers in Nutrition, kissing increases the diversity in gut microbiota, and this is actually beneficial because more diversity can help stave off heart disease, obesity, and diabetes, among other things. If it takes a few extra smooches to reduce your chances of coming down with these ailments at some point, then that’s a good thing. 

However, even before those 80 million bacteria make their way into your stomach, throwing your gut microbiota for a loop, they can do some damage in your mouth. It doesn’t matter how healthy your mouth is or how often you floss and brush your teeth; if you’re kissing someone who’s making oral health mistakes, your mouth is being exposed to harmful bacteria.

“What we have found over recent studies is that cavities or dental decay is actually a communicable disease, meaning it can be passed on from one person to another with close contact,” dentist Dr. Jeffrey Sulitzer told USA Today Life, adding that even kisses that aren’t dripping in saliva can still possibly pass on cavities. Then, despite your perfect dental hygiene, you’ve suddenly got tooth decay, gum disease, and other periodontal issues. If this is the case, then it’s time to introduce your partner to some floss and the importance of brushing after each meal.

As much as kissing is, when you think about it, kinda vile, when you’re in the heat of the moment, in one of those kisses that you know you’re going to remember for the rest of your life, how gross it all is isn’t likely to cross your mind. But now that you know that kissing, not the act, but what’s happening to the body, is pretty nasty, at least you have a source to point to if something in your stomach or mouth becomes a little off.