You do it morning and night and maybe even after meals. It makes your mouth feel clean enough to kiss and helps you smile without feeling self-conscious. Yet if you’re like most people, the number of germs that are lurking on your toothbrush will make you re-think that minty-fresh feeling.
According to a study at the University of Manchester in England, the average toothbrush can contain 10 million or more bacteria—including E. coli (the stuff that lives in our intestines and can cause mild diarrhea—or even vomiting and severe abdominal cramps, if it’s a nasty strain) and Staph (which are mostly harmless but can cause infections). What’s more, at any given time there are 100 to 200 species of oral bacteria living in your mouth—bacteria that end up on your toothbrush.
There’s more to worry about if you store your toothbrush in a cute little cup on the bathroom sink. “If your toothbrush is stored within three feet of the toilet, the droplets of water that spray up after you flush remain airborne long enough to settle on surfaces throughout the bathroom—including your toothbrush—which means you may be cleaning your teeth with what you thought you flushed down the toilet,” says Charles Gerba, Ph.D., a professor of microbiology at the University of Arizona.
Also, if you fall in the camp of not getting skeeved at the thought of sharing a toothbrush with your man, know that the germs you get from a brush can be a lot different than what you swap when you smooch. “Brushing and flossing can create tiny cuts in your mouth, and blood borne viruses, like hepatitis B, are then transferred onto the toothbrush and could then be transmitted to another person who uses the same brush,” says Gerba.
Sufficiently grossed out? Follow this advice from Maria Lopez Howell, a spokesperson for the American Dental Association and a dentist in San Antonio:

Clean Your Toothbrush EVERY Day

Yes, every day. “The point of having a toothbrush is to get bacteria out of your mouth, so you will inherently have some bacteria on it,” says Howell. That’s why it’s important to thoroughly rinse your toothbrush with water after brushing, to remove bacteria as well as any remaining toothpaste or other debris. Keep in mind that you shouldn’t microwave your brush or stick it in the dishwasher; this can damage it and decrease its effectiveness, says Howell.

Buy a New Brush After You’ve Been Sick

There’s no evidence showing that you’ll get sick again if you don’t do this, “but why not err on the side of health?” says Howell.

Replace Your Brush Every 3-4 Months

And you’ll want a new one even sooner if the bristles become frayed and worn, says Howell. “That’s a sign that it’s not going to work as effectively at removing built-up plaque from your teeth and gums,” says Howell. (Note: Kids’ brushes often need replacing more frequently than yours because they’re more likely to chew on them, fraying the bristles.)

Never Store Your Brush Close to the Toilet

And if you have no other choice, at least make sure you close the toilet lid before flushing and move it away from the sink when you wash your hands.

Don’t Keep It in an Airtight Travel Case, Either

Or in the shower or another damp spot that doesn’t get a lot of air and is therefore conducive to the growth of microorganisms. “In an ideal world, you’d store the brush in an upright position in a spot that gets enough air for it to dry between brushings,” says Howell. Quick tip: Howell likes to put her travel toothbrush container in the dishwasher after she uses it. “It’s a great way to keep the container for your brush germ-free and clean,” she says.
RELATED: 7 Surprising Ways You’re Destroying Your Teeth

Don’t Share Toothbrushes

No matter how much you like the guy, it’ll put you both at increased risk for infections. “Just use common sense on this one,” says Howell. “Different people have different amounts of bacteria in their mouths, so why take the risk? Not sharing is caring in this instance.”