When health officials discovered a hepatitis A outbreak in California this summer, they swiftly issued health warnings about how to avoid the disease.

Among the many suggestions: Don’t share toothbrushes.

Yes, people actually do that. In fact, millennials once told pollsters they would be more apt to share their toothbrushes with someone than their cellphones, and an Irish health study revealed that one-third of adults admitted to sharing a toothbrush.

Beyond the “yuck” factor, that’s a bad idea on a lot of different levels health-wise, says Dr. Sanda Moldovan, a certified nutritionist, periodontist and author of the upcoming book, “Heal Up!”

That simple act of sharing a toothbrush can compromise your health in more ways than you might imagine.

“Your mouth is the gateway to your health,” Moldovan says. “Unfortunately, when you share a toothbrush you are opening that gateway to a lot of problems you’d be better off avoiding.”

Many of those problems, she says, are serious and some come with long-term implications. Among the reasons not to share:

Bleeding gums. A toothbrush can easily spread blood-borne illnesses. Why is that? “When some people brush, their gums bleed,” Moldovan says. “That can result in exposure to bacteria and viruses that can enter the bloodstream.”

Bacteria. A toothbrush can harbor streptococcus mutans – the same bacteria responsible for MRSA infections, flesh-eating bacteria, and tooth decay.

Food particles. A toothbrush can exposes you to what someone else ate for dinner, possibly even the day before. That is especially true when that person fails to rinse or brush properly.

Viruses. Viruses such as the herpes simplex type one can be spread with toothbrush use. This is the same virus responsible for oral and genital herpes. Another virus that can spread with toothbrush sharing is HPV (human papillomavirus). That virus is linked to esophageal, oral and cervical cancers.

Fungi. Maybe you don’t think of a toothbrush as a potential petri dish, but fungi such as candida (the fungus responsible for diaper rash and yeast infections) can live on toothbrushes.

Periodontal disease. One of the most common oral infections, periodontitis, can be spread via the toothbrush. There are a lot of implications to that, such as the potential loss of teeth, Moldovan says. “In this case, it’s also not just a problem that’s limited to the mouth,” she says. “Periodontal disease can affect the whole body.”
Many of the problems lurking in those bristles also are good reasons to regularly dispose of your toothbrush and replace it with a new one, Moldovan says.

“There are plenty of things in the world you can share,” she says. “A toothbrush doesn’t need to be one of them.”