The Scientist: Charles Gerba, Ph.D., professor of microbiology and environmental sciences at the University of Arizona
The Answer: Here’s a myth we can put to bed: You don’t have to throw out your toothbrush just because you have been sick. Whether you had the sniffles, a full-blown cold or even strep throat, you can keep cleaning your teeth with the same brush after you’re feeling better.
Can germs live on your toothbrush? Yes, indeed they can, for a few hours up to a few days. And the moist environment provided by a recently rinsed toothbrush is rather hospitable to pathogens—they usually last longer on wet bristles. But as long as they’re your own germs, you don’t have to worry. You’re not going to make yourself sick again if you use the same toothbrush after you’ve recovered. That’s because you’ve built up antibodies over the course of your illness, so whatever is left on the brush will be wiped out upon entering your immune system. If you share your toothbrush, however, you could definitely make someone else sick. That being said, you really shouldn’t share your toothbrush with anyone anyway. If you want to disinfect your toothbrush, you can buy a toothbrush sanitizer that zaps germs with UV light—but simply submerging it in boiling water will do the trick.