Skip navigation
Annenberg School of Communication and Journalism University of Southern California
Your Health

One Kiss Spreads 80 Million Bacteria, New Study Says

A new study shows that couples who kiss regularly develop similar microbiota. 

(Luke Baldacchino/Flickr)
(Luke Baldacchino/Flickr)

A ten-second kiss can transfer 80 million bacteria, a study published in Microbiome Monday shows.

“Intimate kissing involving full tongue contact and saliva exchange appears to be a courtship behavior unique to humans and is common in over 90 percent of known cultures,” said Remco Kort, who led the research. He is a professor of microbial genomics at Amsterdam’s VU University.

Researchers investigated 21 couples by asking them to fill out questionnaires, which include their self-reported kiss history. 

The result shows the more frequently they kiss, the more similar the microbiota in their saliva is likely to be.

In order to develop similar microbiota, “frequent and recent bacterial exchange" is required. This means that similar microbiota profiles are usually found in couples who have a relatively high frequencies of intimate kissing. 


Leave a comment

We've Moved!

By Sam Bergum
01/21/16 | 11:09 a.m. PST

Visit us at!

USC Basketball Knocks Off Rival UCLA 89- 75

By Scott Cook
01/14/16 | 12:05 a.m. PST

USC defeats UCLA with stellar play from their Freshmen. 

Holiday Bowl - USC vs Wisconsin Post-Game Press Conference

Su'a Cravens: "It's the players that need to step up"

Darreus Rogers: "It comes down to the players"

Trojans Fall to Wisconsin in the Holiday Bowl 23-21

We detected that you might be on a mobile device such as an iPad or iPhone. Sorry, at this time the video box is only visible on desktop computers.