How often should you wash your gym wear?

I have a confession to make. I don’t always wash my workout clothes right away after exercising. If I’ve had a really sweaty session, they’ll go straight into the laundry—but otherwise I’ll rewear them at least once. Think about it: A hot girl walk on a crisp day or a quick 15 to 20 minutes on a Peloton bike that doesn’t result in much sweat shouldn’t mean I have to do more laundry this week.

That’s my “girl math” logic, but I had to find out from an expert if it’s actually safe for my skin. Is my “reuse” habit causing more harm than I realize? I spoke with a dermatologist about what we should all keep in mind when deciding whether to toss activewear in the laundry.

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The real concern is sweat, bacteria, and acne

On its own, sweat is pretty harmless and odorless. But when it combines with the naturally occurring bacteria on your skin and is absorbed by fabric, that’s when things can start to smell and irritate. The problems arise when you keep your sweaty clothes on for hours after your workout.

“The longer the bacteria stays in contact with your skin, the higher chance it can become harmful,” Brianna Olamiju, MD, FAAD, a New York–based dermatologist, tells SELF.

“Usually, it can cause acne. I see a lot of patients who have breakouts on their chest or back, often people who work out frequently and maybe go to brunch afterwards or aren’t able to change or wash immediately.”

And unfortunately for me, Dr. Olamiju says that even if you remove your activewear then rewear it the next day, bacteria doesn’t just disappear. “Some of the bacteria from the prior workout can still linger,” she says. “It’s probably going to smell, but it can also still cause acne or irritation.”

It depends on your workout—and your activewear

Okay, my logic wasn’t totally off. Dr. Olamiju says not all workouts are created equal when it comes to sweat and skin risk. Just as I suspected, the sweatier workouts (like running, hot yoga, or spin class) are the ones that warrant a fresh set of clothing tomorrow.

“High-intensity cardio tends to cause the most sweat,” Dr. Olamiju says. “Those are at higher risk for acne. Lower intensity workouts, like Pilates, walking, or yoga, may be lower risk. Everyone sweats differently, so it’s on a spectrum.”

When it comes to deciding which clothing items need a wash, Dr. Olamiju singles out a few items that are prone to becoming especially stinky. “For women, changing your sports bra is really essential. The shirt you might get away with wearing again, but the sports bra and underwear are the pieces you really want to change.”

She also points out that fabrics do, in fact, matter. “Most workout clothing has polyester, which traps sweat. Cotton is more breathable and less risky if you want to reuse clothes. But it can be harder to find cotton activewear.”

Hygiene tips for workout wear

So how often should we really wash our workout wear? “The dermatologist's answer is after every workout,” Dr. Olamiju says. “But people can use their own discretion—think about how comfortable you feel.”

In other words, washing after every wear is the gold standard, but there’s some wiggle room depending on how much you sweat and how you handle your clothes post-workout. If you’re hoping to get another wear out of your gear, here’s how to do it in the most skin-friendly way:

Default to washing after sweaty workouts: Think high-intensity cardio, heated classes, or outdoor runs—anything where you’re drenched should go straight in the laundry.
Be strategic about what you rewear: Items like sports bras, underwear, and socks should always be changed after each workout, since they sit closest to your skin, Dr. Olamiju says.
Let clothes fully dry before wearing them again: Tossing damp leggings in a pile creates the perfect environment for bacteria to thrive. Instead, hang them up in a well-ventilated area so air can circulate.
Don’t delay changing out of sweaty clothes: If you sit around in them for a while post-workout, it’s best not to rewear them—the longer they stay on your body, the more time bacteria has to build up.
Do a sniff (and feel) test: If it smells even a little off or still feels damp, skip the rewear.
Try an antibacterial refresh: Hypochlorous acid sprays or activewear mists can help cut down on bacteria between washes. As Dr. Olamiju notes, they’re “supposed to help kill bacteria and prevent acne.”
Watch your gym hygiene: Wipe down shared mats before use, and avoid going barefoot when possible—“ringworm can be a risk,” Dr. Olamiju says.

You don’t have to stress over every single wear (phew!), but a few smart habits go a long way. When in doubt, err on the side of fresh—your skin will thank you.

Original article appeared on SELF