It’s best not to ruminate about how much bacteria are on your toothbrush.  Chances are its chock full of them from the first time you use it.  But germs aren’t really the problem, says Jeffery Hobden, PhD, Assistant Professor of Microbiology, Immunology, and Parasitology at LSU Health Sciences Center New Orleans. “Besides the ick factor of having bacteria on your toothbrush, it’s your bacteria,” says Hobden. But your housemate’s germs are another story—keep toothbrushes from touching if sharing the same holder to prevent cross-contamination.

It’s time to replace a toothbrush when it’s no longer able to effectively remove the plaque from your teeth, which is about every three to four months, according to the American Dental Association.  A faulty toothbrush can leave buildup on your teeth and gums, resulting in inflammation leading to gum disease.

Oh Sh@$!!

Concern about fecal matter floating onto toothbrushes in the close quarters of a bathroom has been the focus of a few studies.  True, fecal coliforms can attach to toothbrushes, but do not multiply enough to make you sick.  Plastic covers are usually unnecessary and can even be counterproductive if put on when toothbrushes are wet.  Instead, ADA suggests soaking a toothbrush in antimicrobial mouthwash for a few minutes to cut down on germs.