Chances are you've been to the gym and made this mistake — and experts are warning it can have damning ramifications if you don't stop.
While taking a towel for your workout is a must-have, how you use it is where the problem lies.
Most of us will use it to clean the equipment after sweating all over it. But then we'll use the same dirty towel to wipe our face, reports News.com.au.
Australian natural beauty expert Belinda Hughes said not only was it a "gross" habit, but it could be causing you some serious skin issues.
"You're transferring workout bacteria straight onto your face, which besides being gross can lead to skin conditions like acne and even fungal infections on the skin," Ms Hughes told news.com.au.
The Melbourne-based skin correction specialist said it was important to carry a travel-sized face wash and moisturiser in your gym bag, especially for those already suffering from a skin condition.
"After your workout, when you're in the shower, you should use a face wash to treat your skin properly. If you don't, it can potentially flare up, especially if you have a skin condition you're trying to manage."
Amy Broderick, an advanced dermal therapist, said gyms, locker rooms and saunas were the optimal breeding grounds for bacteria to grow.
"It really is super important to not use the same towel on your face as you do on gym equipment," Ms Broderick also advised.
"Imagine how many people have used the machinery, benches, yoga mats or floor before you that day alone?
"If you are using the same towel to wipe your face after using it in the gym, you put yourself at risk of developing bacterial breakouts or fungal infections."
Instead, she said to pack either a separate towel for your face or even some disposable cotton rounds to keep things hygienic.
"Some of my other favourite hygiene tips for gym-goers are to keep your hair (and hands) off your face, shower immediately after to avoid congested skin or infections and don't forget to wash your gym bag."
KAYLA ITSINES ENCOURAGES GYM GOERS TO TAKE TWO TOWELS
Earlier this year, fitness guru and creator of the Bikini Body Guide Kayla Itsines urged her 11 million social media followers to pack two towels when going to the gym after she suffered painful breakouts.
The 28-year-old shared a selfie of her skin flared red with pimples and explained that poor hygiene practices at the gym made them difficult to get rid of.
"Do not touch your skin at the gym," the mother-of-one captioned the images.
"I was so upset in this photo, my skin was so sore. The other side of my face was so much worse, but I was too embarrassed to take a photo of it."
The Aussie fitness influencer, worth $487 million said to wash your hands if you touched equipment like treadmill handles, and mats at the gym were covered in sweat too.
"Do not use the same towel you use to put on the benches to wipe your face with," she insisted.
Itsines then recommended a bunch of products she used to fight acne.
"Under $15 you can buy Cetaphil for oily skin, and that gets your make-up off, and that's what I use. Cetaphil, one quick wash and it gets my make-up off," she said.
She said the Envy U Skincare charcoal exfoliator helped "fix my skin".
Itsines uses it alongside the Foreo Luna Go For Normal Skin tool, which costs $149 and provides an extra layer of cleansing.
Her go-to moisturiser (for sensitive skin) is La Roche-Posay ($31.99) – a French brand she said helped her pregnancy dermatitis hugely.
TRAINING WITH YOUR MAKE-UP ON
According to New York-based dermatologist Rachel Nazarian, working out with your make-up on is a big no-no.
Why? Because exercising causes blood vessels to expand, increases blood flow to the skin, and opens pores.
"Sweat and bacteria get trapped under layers of make-up, preventing the skin from dissipating heat properly and leaving it prone to pore occlusion (or becoming majorly clogged)," Ms Nazarian told Health.com
"The trapping of bacteria and sweat in the (now dilated) pores can enlarge pores over time and cause blackheads, while the trapping of heat can flare temperature-sensitive conditions such as rosacea, ultimately causing redness and uneven skin tone."
Ms Hughes, who has been practising in the skin field for 15 years, understands women can be in a rush, particularly if exercising while on a lunch break.
"If you must, use a mineral make-up but I highly discourage, it especially if you have acne," she said.
According to renowned New York-based dermatologist Whitney Bowe, sweat-proof make-up does not make a difference.
"When sweat is mixed with make-up (no matter what type of make-up), it creates an ideal environment for acne," Ms Bowe told Instyle.