Yes, when you kiss someone, especially deeply (French kissing), you exchange saliva and the microorganisms within it, transferring millions of bacteria and potentially viruses, which can also swap DNA and shape your oral microbiomes over time, according to studies from Better Health Channel, National Institutes of Health (NIH) | (.gov), Colgate, and Springer Nature Link. While most transferred microbes are harmless and can even boost immunity, some illnesses like the common cold, mono, or herpes can spread this way, notes Hawaii Family Dental.
Bacteria and viruses in the saliva or blood of one person can be spread to another person by kissing. Some diseases are more easily spread than others.
While there is no way to kiss someone without swapping some saliva, there are numerous ways you and your partner can help protect each other from bad bacteria.
No matter how fleeting the encounter, the DNA will hang around in their mouth for at least an hour. This means that women's saliva could contain evidence of unwanted attention in cases of assault, or even telltale signs of infidelity.
One kiss transfers around 80 million bacteria. Kiss the same person about 9 times a day, and your saliva microbiome starts to look almost identical. This isn't romance - it's science. A study published in Microbiome found that couples begin to share and blend their oral bacteria over time.
The 90/10 kissing rule, popularized by the movie Hitch, suggests that one person leans in 90% of the way for a kiss and pauses, allowing the other person to close the remaining 10%, which signals their consent and involvement, preventing it from feeling forced and creating anticipation. This technique gives the other person control, allowing them to either lean in for the kiss or pull away, indicating their comfort level.
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Oxytocin – The Bonding Hormone
When you kiss, your brain releases oxytocin [4], which can make you feel calm, happy, and safe. It also lowers stress and anxiety, which is why kissing often feels so comforting, especially during tough times.
Partners who had kissed very recently had more similar saliva microbiomes, whereas if many hours had passed since last contact, their saliva communities became more dissimilar.
Steps
Some signs you're a bad kisser: Going too fast, lacking enthusiasm, poor technique, and bad breath are common indicators. How to not be a bad kisser: Start slow, use your body to add dimension, focus on your partner's reactions, and ask for feedback to improve.
You know that “icky vs. euphoric” kiss split? Part of it is chemistry you can literally taste. Saliva isn't just spit; it's packed with signals—free hormone traces, metabolites, and yes, DNA from sloughed cheek cells.
When you kiss someone you care about, dopamine is released in the brain, stimulating the same area associated with pleasure and reward.
Enjoy the moment slowly, without worrying about next steps.
While everyone produces a different amount of saliva, you can control the amount that ends up on your kissing partner's face. Try not to push too much saliva out of your mouth while kissing and be careful with how wide the motions of your mouth are. If you're getting their chin wet, you've probably gone too far.
A kiss with the tongue stimulates the partner's lips, tongue and mouth, which are sensitive to the touch and induce sexual arousal. The sensation when two tongues touch—also known as tongue touching—has been proven to stimulate endorphin release and reduce acute stress levels.
They feel more passion and desire – Tongue kisses are often linked to deeper intimacy and attraction. 🤝 They want stronger connection – It can be their way of showing closeness and wanting to bond emotionally.
You'll probably also notice that he's blushing or breathing a little more heavily. A passionate makeout session releases adrenaline–not only does it kick up his heart rate, but it also boosts his energy. Check if he suddenly seems happy and hyper.
The Netherlands Organisation for Applied Scientific Research succeeded to count the bacteria jumping from tongue to tongue and published on Microbiome a study that revealed incredible results: 80 million bacteria and 700 different strains are exchanged with each kiss!
But it does provide some rough guidelines as to how soon may be too soon to make long-term commitments and how long may be too long to stick with a relationship. Each of the three numbers—three, six, and nine—stands for the month that a different common stage of a relationship tends to end.
Sensing the hubbub, the adrenal glands unleash adrenaline. Cue a pounding heart, heavy breathing, or sweaty palms. (If you two become a couple, kissing could eventually trigger an opposite effect—peace instead of passion.)
Nape of the Neck: Place soft kisses along the nape, moving slowly from the hairline downward. Lightly graze the area with your teeth or fingertips. Side of the Neck: Kiss and lick the sides of the neck, alternating with gentle sucking. Pay attention to your partner's reactions to find the most sensitive spots.
They are...
The 7-7-7 rule for couples is a guideline for maintaining strong connection by scheduling dedicated time: a date night every 7 days, a weekend getaway (or night away) every 7 weeks, and a longer, kid-free vacation every 7 months, all designed to fight drift and routine by ensuring consistent, intentional quality time, though flexibility is key.
A strong and healthy relationship is built on the three C's: Communication, Compromise and Commitment. Think about how to use communication to make your partner feel needed, desired and appreciated.