From thick mustaches to bristly beards, full-on facial hair is 2015's style trend for men. And not to totally scare you away from a guy who sports the lumberjack look, but his unshaven face might be hiding an unhygienic secret.

Though the risk is small, chin and cheek hair can harbor germs that can cause icky things like herpes, fungal infections, or even a dangerous staph infection. Make direct contact with one of these bugs, and you may end up with skin issues of your own.

"If a guy doesn't groom his mustache and beard properly, they can become a breeding grounds for germs," says Debra Jaliman, M.D., a dermatologist in New York City. That's partly because the wiry hairs trap sweat, bodily fluids, even bits of food, all of which serve as cafeterias for microbes that may then be served up to you.

Another problem, Jaliman says, is that thick facial hair can camouflage symptoms of a transmissible skin issue that isn't directly related to the beard or mustache itself, such as redness that could be from yeast or a herpes sore. If he doesn't notice the signs, he could inadvertently transmit the condition to you.

Other things you can get from hipster facial hair include warts, as well as a bacterial skin condition called impetigo that leads to angry red open sores, says New York City dermatologist Diane Berson, M.D. "And of course, a bristly beard can cause irritation and a rash when rubbed against his partner's face, which can trigger pink bumps and chafing," she says.

But there's no need to force your guy to razor it all off—just take a few smart steps to lower your infection odds. First, encourage him to groom his facial hair right, which means washing it with soap in the shower at least once a day and inspecting it regularly (like after meals) to make sure no particles or dirt are trapped between the hairs.

And before you engage in any direct contact with his unshaven mug, give it a quick once-over to make sure the skin around and under it is healthy, with no redness, bumps, or blisters. "Men aren't always used to taking care of body hair, and they don't necessarily clean it well," says Jaliman. Gross but true, so to keep your skin infection-free, follow due diligence.