New research reveals that a single 10-second smooch can pass 80 million bacteria between partners. Doctors shed some light
Lips don’t lie, they just kiss! Whether you kiss and make up or kiss and wake up with your partner, there is nothing as sublime as an intense kiss. But beneath the tenderness of a kiss, there’s something else happening. Romance, it turns out, is a microbial event! New research claims that a single 10-second smooch can lead to the exchange of 80 million bacteria.
“Intimate kissing can transfer saliva, which contains oral bacteria and microbes,” explains Dr. N D Padmakar, Senior Consultant Urologist and Andrologist, Renova Century Hospitals from Hyderabad.
While most of these bacterial spurts are harmless, some can cause infections, especially when there are mouth sores, gum disease, or existing oral infections.
This latest kiss-and-tell tale has sent shockwaves across social media and caused a tizzy among youngsters. In a TikTok video, renowned NHS surgical doctor Dr Karan Raj says: “The next time you pucker up and swap saliva with someone’s face hole, just know you’re gifting each other 80 million bacteria in one kiss.”
Kiss & Tell
A study conducted by researchers from the Netherlands Organization for Applied Scientific Research (TNO) revealed that a 10-second kiss can transfer up to 80 million bacteria between partners. The Dutch scientists published a study in the journal Microbiome, which put a kiss under the microscope —quite literally — and uncovered its lesser-known microbial side. By sampling bacterial populations from volunteers’ tongues and saliva before and after a strictly timed 10-second kiss, researchers let science lock lips with romance.
What they found was nothing short of jaw-dropping. By the second monitored kiss, the exchange became measurable and memorable. In just 10 seconds of lip service, an average of 80 million bacteria made the leap from one partner to the other. Proof, perhaps, that when sparks fly, microbes tag along too.
Our mouths are like cities – warm, moist and densely populated by bacteria. Over 700 species of bacteria live there, forming communities as complex as any human society. Some are lifelong residents, while others are passerbys.
Dr Tanaya Narendra (Dr Cuterus), MBBS and FRSPH says, “Bacteria are not inherently bad. There are bacteria that are important for us to live and survive.” She explains that kissing, per se, without an active infection, doesn’t lead to a cause for worry. However, there are instances where caution is needed.
Peck Problems
“Among the most common diseases that can be transmitted through kissing are Glandular fever, herpes infection including cold sores, chicken pox, Hepatitis B virus and many others, causing tooth decay,” says Dr. T Vivek, Consultant Interventional Pulmonologist, Renova Century Hospitals from Hyderabad. Dr Vivek opines that in rare but serious cases, meningococcal meningitis — a potentially life-threatening condition causing inflammation of the brain and spinal cord — may spread through close contact, including deep kissing.
However, Dr Vivek explains that for most healthy individuals, the exchange of microorganisms during kissing is usually harmless and rarely leads to illness. But the risk rises when one partner is actively infected, immunocompromised, or has open sores or gum disease. In such cases, saliva can act as a carrier for pathogens, potentially leading to infections. Point being, the overall health impact depends largely on an individual’s immune status, oral hygiene, and the presence of any active infection at the time of contact.
Dr Tanaya seconds this, “For individuals with good oral health, this isn’t really a risk. Our bodies aren’t sterile; bacteria are already living on us, so such an exchange is just bacteria shifting location, not necessarily spreading infection.” She adds, “However, kissing can transmit infections if a pre-existing condition or infection is present.” Dr. Vivek notes, “Unfortunately, discussions on sexual health, including kissing, are still considered taboo and often embarrassing.”
Pucker Up Carefully
Dr Padmakar says, “Awareness, preventive care, and caution are crucial, as many may not realize how easily infections spread through close contact.” Simple, consistent precautions — including using protection when a partner’s health status is uncertain — can significantly reduce the risk of transmission during intimacy. He emphasizes that maintaining good oral hygiene — through regular brushing, flossing, and appropriate mouth rinses — reduces harmful microbes in the mouth and helps prevent oral infections. Equally important is having open and honest communication with one’s partner about symptoms, exposures, or concerns to minimize avoidable risks.
Dr. Tanaya cautions that oral sex is not risk-free. Using protection — condoms for male partners and dental dams for female partners — is essential, as sexually transmitted infections can be easily transmitted through oral sexual activity.
Sealed With A Kiss
So no, a kiss isn’t the culprit. It’s the carelessness that causes concern. An exchange of 80 million bacteria may sound like microbial mayhem, but lips aren’t loaded weapons. Not unless an infection is already in play!
Kissing is a natural thing, not a crime scene. Just keep up good oral hygiene and seal it with a healthy kiss!
