Your toothbrush is home to plaque, blood and even fecal matter.
Yes, you're probably scrubbing poop particles all over your pearly whites.
Miryam Wahram, author of The Hand Book: Surviving in a Germ-Filled World, said a toothbrush “could be much worse than a toilet seat” in terms of germs. A 2012 study by Manchester University in England says it's much worse — more than 10 million bacteria call your toothbrush home.
"There are real concerns, if you have it in the bathroom," she said. "As you flush the toilet it, you expose your toothbrush to germs from the fecal matter."
MythBusters found toothbrushes sitting outside a bathroom can be speckled with fecal matter, too. In fact, toothbrushes right out of the box can harbor bacteria because they aren't sold in sterile packaging.
Before you toss your toothbrush in horror, know that most germs (including those from a toilet plume) won't hurt you as long as you are using toothpaste. Not brushing would do a lot more damage to your health.
How you store your toothbrush is often what really matters. The American Dental Association recommends rinsing toothbrushes with tap water after use and air drying. Covering brushes contains moisture, which could harbor more bacteria.
The best way to prevent toilet water from splashing your toothbrush? Close the lid before you flush, Wahram said.
Germaphobes could also rinse toothbrushes in antibacterial mouthwash or toothbrush sanitizer (but, the ADA says those don't really make a big difference).
To keep germs at bay, don't let anyone else use your toothbrush and buy a new one every three to four months (or earlier if the bristles become frayed).