Is Sharing a Toothbrush Really More Unhygienic Than Sharing a Kiss?

According to a dental professor, each comes with its own set of (gross) risks.

Is Sharing a Toothbrush Really More Unhygienic Than Sharing a Kiss?

We’re funny creatures, us humans. We’ll happily lick, slurp and nibble another human all over their body, but the suggestion of using their toothbrush afterwards is, for many of us, a step too far. But is this sudden blech at the thought of your partner’s germs justified? According to Dr. Mark Ryder, DMD, R. Earl Robinson Professor and chair of the Division of Periodontology in the UCSF School of Dentistry: No.

“Sharing a toothbrush is probably about the same as kissing,” says Ryder, when asked about the risks of swapping infections. “The difference with a kiss is that you’re transmitting saliva, too, so the bacteria may be able to survive a little better in that saliva.”

This doesn’t mean that kissing is worse than sharing a toothbrush—it’s just a different form of risk. “With a toothbrush, although you’re actually putting the bacteria a little closer to the gum and around the tooth, a lot of those bacteria are probably going to die off on the toothbrush before they go from one person to the next,” says Ryder. “One kind of balances out the other: With a toothbrush, you’re pushing it closer to where you don’t want it to be. With a kiss, maybe more of the bacteria can survive going from one person to another.”

When it comes to something more serious than everyday bacteria, however, the toothbrush can become more problematic. “If one person has bleeding gums and hepatitis, that virus might last a little longer on the toothbrush,” warns Ryder. “If you now brush your teeth and you have a cut in your mouth, some of that virus may get into your bloodstream.” His advice on staying safe? “I would say the bottom line is to keep your teeth clean if you have an active sex life. And don’t be so cheap! Get another toothbrush.”

There are, of course, situations where you might consider sharing a toothbrush with someone you’re not regularly smooching. If you crashed at a buddy’s place the night before and want to clean the taste of beer and pizza out of your mouth, should you consider using their toothbrush? “The chances of getting something are extremely rare, but I would wait till you get home and use your own toothbrush,” says Ryder. Alternatively, he recommends borrowing a clean washcloth, wrapping it round your finger, wetting it and cleaning your teeth with that. You can also run a toothpick across your teeth and along your gum line, or just use mouthwash.

Just remember, there are more things than the other person’s mouth germs to worry about when using their toothbrush: Toilet flush blast radius is a very real thing.