Toothbrushes should be clean: After all, their whole purpose is to scrub all the germs out of your mouth. But as it turns out, dirty toothbrushes could make you sick.

“Bathrooms are moist and steamy: the conditions that bacteria love,” says Carol Wooden, a dental surgeon and spokesperson for the Academy of General Dentistry. Research from the University of Birmingham School of Dentistry in the United Kingdom found as many as 1.2 million bacteria on a single toothbrush, while a recent study in the New York State Dental Journal that examined used toothbrushes discovered that 70 percent were heavily contaminated with different microorganisms.

The Filthy 5

These are five of the nastiest germs scientists have found hanging out on toothbrushes:

Flu:

Influenza causes fever, chills, coughing and achiness.

Staph:

Staphylococcus aureus is responsible for common skin infections (such as boils and styes) and can be more problematic if it enters your bloodstream.

E. coli:

Certain strains of these fecal bacteria can cause diarrhea and abdominal cramps.

Yeast:

Candida albicans (the fungus that causes yeast infections) was found on 70 percent of toothbrushes examined in a recent study from the University of Adelaide in Australia.

Strep:

Some kinds of streptococci bacteria lead to tooth decay; others (you guessed it) cause strep throat.

Healthy Toothbrush Tips

Fortunately, you probably don’t need to toss your toothbrush just yet. Even though certain germs have been identified on toothbrushes, that doesn’t mean you’ll catch something simply from polishing your pearly whites, according to the Centers for Disease Control and Prevention.

“As long as you practice proper hygiene habits, it’s unlikely that bacteria on your toothbrush will make you sick,” says Dr. Neil Schachter, medical director of the respiratory care department at Mount Sinai Medical Center in New York City and author of The Good Doctor's Guide to Colds and Flu.

Follow these four rules to stay healthy:

1. Swap your brush.

Replace your toothbrush (or the changeable head if you use an electric one) every three months, whenever you have a cold or the flu, or when the bristles look worn, suggests Wooden.

2. Flush carefully.

Microorganisms go airborne when you flush the toilet -- and they can land on your toothbrush. Keep your brush as far from the loo as possible and always close the lid before flushing.

3. Keep it to yourself.

“Sharing toothbrushes can spread bacteria and viruses,” says Schachter. Even storing your toothbrush too close to someone else’s is unwise because bacteria can jump from one brush to another

4. Wash away germs.

Since bacteria from your mouth are transferred to your toothbrush every time you brush, you should always rinse your brush thoroughly afterward. “My main health concern is that small amounts of food can remain in the bristles, and if they’re not removed, they can spoil and cause gastrointestinal problems,” says Schachter. “It’s best to rinse your toothbrush in hot water after each use.” Want something stronger than water? Try dunking your brush in hydrogen peroxide or mouthwash, rinsing it with water and letting it air-dry, says Wooden.

Available at Amazon.com:

The Good Doctor's Guide to Colds and Flu

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