It doesn’t take a whole lot to get psyched for summer—especially after the winter most of the country has just had. But maybe one of the best reasons to welcome the warm days ahead is being able to release our feet from the bondage of bulky boots and toe-cramming stilettos and slide into summer’s go-to shoe: flip-flops.

But hedonists, beware: Those laid-back little numbers can play havoc on your feet. And, for that matter, your face.

Exhibit A: Brad Pitt, who has been sporting a nasty bruise under his left eye. For days, there was speculation on just how it got there. Did he get hurt doing his own stunts? Nope. Maybe a “misunderstanding” with the missus? Nah. “This is what happens when you try to run up steps in the dark, with your arms full, wearing flip-flops,” Pitt told People. “Turns out if you then try to stop your forward momentum with your face, the result is a road rash.”

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Burned by rubber. Why are we not surprised? Let’s face it: We’ve all gotten a little too, well, comfortable with this flimsy footwear. Originally designed to be worn at the beach and neighborhood pool, or on leisurely neighborhood strolls, flip-flops have been showing up pretty much everywhere. Call it the “Minimalist Movement.”

Girls wear them to their proms; celebs on the red carpet. In 2005, members of the Northwestern University championship women’s lacrosse team wore flip-flops to meet George Bush at the White House—and caught a lot of flack. Heck, Sarah Michelle Gellar even got hitched in them a decade ago.

Those things are more a matter of fashion sense—or lack thereof. But here is where things get kind of dicey: “I can remember walking up a steep mountain in California and seeing other climbers wearing flip-flops, and falling out of them,” said Dr. Corinne Kauderer, a Brooklyn-based board-certified podiatrist and former president of the American Association for Women Podiatrists (AAWP).

She’s not kidding. Check out this little gem in a National Geographic story called Hiker Mistakes That Can Ruin Your Grand Canyon Vacation… or Worse: Often times when you take a few steps along the Bright Angel Trail at the Grand Canyon you can see them: people trudging down the well-trodden path to get an impression of the interior of the famous gorge with nothing more than flip-flops and spaghetti straps shirts.

The Grand Canyon? Seriously, people?? OK, clearly it’s time for an intervention. Here are (at least) seven situations when you should never, ever wear flip-flops:

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Walking the dog
Simply put, flip-flops are germ magnets. All it takes is a 30-minute stroll with Buster or an afternoon puttering around in your backyard garden to get your feet good and dirty.

“Flip-flops may be better than going barefoot,” Kauderer said, “but even so, much of your foot is exposed to dirt and bacteria, which increases your chances of getting an infection.”

In fact—prepared to be skeeved out—a 2009 Today Show report found that more than 18,000 types of bacteria were discovered on one pair of flip-flops, including bacteria traces from fecal matter (please, please tell us that was from a dog).

“For those with diabetes, it’s especially dangerous, since they are at an even higher risk of infection,” Kauderer said.

Cruising the Interstate
Not the thing to be wearing when quick reflexes are required.

“It’s all to easy for flip-flops to slip off your feet and lodge under the brake or gas pedal,” said Dr. Megan Leahy, DPM, from the Illinois Bone & Joint Institute.

Hiking, running after kids—or, merely running (right, Brad?)
Flip-flops can turn even the most agile person into a complete klutz. Why: Basically, the only thing holding those rubber soles on your feet is a thin strip of rubber or leather that fits between your first and second toe (known in the fashion trade as a “toe plug”) and 10 clenched toes. According to a 2008 Auburn University study, that leads to shorter strides, which can up the odds that you’ll be kissing pavement.

More scariness: “Changing your gait can lead to problems with your spine, hips, knees and ankles down the road,” Leahy said.

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Doing yardwork
Lawn mowers, weed whackers…enough said. Unless you’re looking for colorful cocktail party chitchat about how you lost two of your toes, keep your feet covered and out of harm’s way.

Standing behind a cash register or waiting in line at the DMV
OK, you may not be feeling the pain now, but trust us, somewhere down the road, you will.

“These pancake flat shoes just don’t give you the support or cushioning you need,” Kauderer said—and that can lead to a lot of different foot problems over time, including plantar fasciitis (an inflammation of tissue on the bottom of the foot), metatarsalgia (pain and inflammation in the ball of the foot), fallen arches, and bone spurs.

Cooking
There’s a reason Mario Batali wears Crocs in the kitchen: Boiling water, bacon grease, sharp pointy utensils—all accidents waiting to happen.

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A crowded subway or bus
There’s always some lead-footed clod who’s not watching where he’s putting his Wingtips. And flip-flops leave your toes so…exposed.

That doesn’t mean you have to ditch your slap-happy pair, says Dr. Kauderer; just choose your moments carefully.

“And if you are planning on wearing them for an extended period of time, look for flip-flops that offer proper support,” she said. Check out this list from the American Podiatric Medical Association (APMA).

One more thing: Don’t forget the sunscreen: All of that exposed skin is susceptible to UV damage

This article originally appeared on Health.com.