When buying clothes, it's easy to assume that "brand new" equals "spotless", but this isn't always the case. At the very least, think about how many hands have touched the t-shirt or dress you just bought - just one reason why giving new clothes a spin in the washing machine before wearing them is a good idea. 

Cleanliness aside, there is another reason why we should perhaps start washing our new clothes before wearing them. Speaking to Time, Dr. Susan Nedorost, a professor of dermatology at Case Western Reserve University says that wearing new clothes can lead to contact dermatitis. 

Should you wash your new clothes before wearing them?

Contact dermatitis is a form of eczema, according to the HSE, which occurs when the skin comes into contact with a substance that irritates it, causing a red, itchy and scaly rash skin, and sometimes burning and stinging. 

Nedorost says that "When we see allergic contact dermatitis from clothing, it's usually from disperse dyes" - dyes that are commonly used in synthetic materials like polyester and nylon. 

This is the material very commonly used in workout gear, especially the stretchy, water-resistant kind. In fact, Nedorost says that "If a patient comes in and has a rash around the back of the neck and along their sides around their armpits, the first question I ask is what they wear when they work out". 

This is because movement, friction and sweating causes more of the dye to leech out and onto skin, possibly causing irritation. 

Certain synthetic clothes can cause contact dermatitis

If you've ever hand-washed a new dress or top, you might have seen how much dye can leech out in that first wash - something you might not have noticed if you chucked them into the washing machine. Clearing some of the disperse dye out of clothes might help you avoid developing a nasty rash. 

"By washing new clothing, you might remove a little extra dye and so have a lower exposure," Nedorost says.

If you've developed contact dermatitis, there are a few simple ways to treat it and avoid it in future. The HSE recommends applying an emollient or moisturiser to the irritated area, to reduce the loss of water from the skin. In severe cases, corticosteroid medicines can be used. 

However, one of the most efficient ways of treating it is, of course, to avoid the allergens that cause irritations. So, if you think your synthetic workout gear is giving you a rash, switch to cotton, and maybe give new clothes a quick rinse before wearing them!

For more information on contact dermatitis, read the HSE's guide here