If you use your towels way longer than you probably should, you’re not alone: You use ’em to wipe off your clean body, after all—what’s the harm in that? Well, basically the terry-cloth drying drapes a breeding ground for bacteria—and not the good kind.

Even when your towels still feel (and smell!) clean, they’re probably dirty. And, whether they’re the small variety for your hands or full-size shower towels, the cloths can become packed with disease-spreading microbes (which are also found in your bedsheets) within a mere few days. Especially when they’re hanging out to dry in damp, warm areas—which is how most bathrooms feel after someone takes a hot rinse.

90 percent of bathroom towels were contaminated with coliform bacteria, and 14 percent were found to carry E. coli.

In fact, you’d be surprised by just how much bacteria is hanging out. Microbiologist Charles Gerba, PhD, told Time that in one unreleased study, 90 percent of bathroom towels were contaminated with coliform bacteria—bacteria found in water that indicate disease-causing organisms could be present—and 14 percent were found to carry E. coli. And—yes, there’s even more—moist towels were found to be breeding ground for MRSA, said Susan Whittier, PhD, and having cuts or dry skin can make it easier for the bacteria to get into your body, which can cause infection.

According to Dr. Gerba, it’s best to wash bathroom towels with bacteria-fighting hot water and activated oxygen bleach (or a bleach alternative) after two days of use.

The only real way to keep your body free of harmful bacteria is to do what no one likes doing: laundry—and, more of it than you’re probably used to. According to Dr. Gerba, it’s best to wash bathroom towels with bacteria-fighting hot water and activated oxygen bleach after two days of use. (And if bleach isn’t your thing, try an alternative like disinfecting lemon juice, stain-fighting vinegar, or hydrogen peroxide.)

If you can’t commit to so many spin cycles, at least make sure to let your towels completely dry between uses, which makes it nearly impossible to pass around bacteria, said Dr. Gerba.

But that won’t help make the towels any less stinky after multiple uses, so you might want to become besties with your washer and dryer anyway.

Not all bacteria is bad, and adding this kind into your diet can actually help you stay healthy. Or, maybe just start spraying some bacteria around your home.