Is dirty underwear really so bad for you?

Few people actually enjoy wearing dirty underwear — but sometimes, it happens. Maybe the airline lost your luggage, or you ended up camping one more night than you initially planned. You can’t always have an emergency pair of underwear on hand. But is it really that terrible if you rewear a pair that is not so fresh?

Dr. Joshua Zeichner, a dermatologist in New York City, tells Yahoo Life that clothing that comes in direct contact with the body — like underwear — should be washed after every wear, since skin oils, sweat and bacteria can transfer directly onto the garment. Washing underwear is particularly important, he says, because it sits in “sweaty areas and is more likely to become soiled with body fluids.”

It’s no surprise that underwear isn’t exactly the cleanest item of laundry. Its purpose is to protect the rest of your clothes from urine, feces and sweat. In fact, a study found that if you did a laundry load of just underwear, there would be about 100 million E. coli in the wash water.

What are the risks of wearing dirty underwear?

Soiled undies can increase the likelihood of developing a bacterial infection, such as a urinary tract infection, as there’s a lot of bacteria that remains on your underwear. It can also lead to a fungal infection, such as a yeast infection or “jock itch,” which is contagious. Fungus thrives in a warm, moist environment, and the longer you wear your underwear without changing it, the more sweat it catches, leading to a fertile home for fungus. Plus, dirty underwear can make you stink since you’re trapping all that sweat and bacteria and creating a breeding ground of funkiness.

Dirty underwear can also increase your risk of skin irritation and inflammation, such as contact dermatitis, which is when something on your skin triggers a rash. It can also come from prolonged wear of even clean underwear. Contact dermatitis may occur if you happen to be allergic to dyes or fabrics in your underwear (or your laundry detergent), so if you’re experiencing skin issues with clean undies, it’s important to check if something may be irritating you.

When should you change your underwear?

While Zeichner says there isn’t a “hard and fast rule,” he recommends changing your underwear every 24 hours, or after an activity that causes sweating, such as working out. Dr. Kautilya Shaurya, a dermatologist at Schweiger Dermatology Group in New York City, tells Yahoo Life that you also want to put on a new pair of underwear after you’ve taken a shower, in order to stay clean, and after your underwear has gotten wet, in order to prevent skin irritation.

There are certain people who may want to change their underwear more frequently, notes Zeichner. If you tend to sweat profusely, you may want to change more regularly. If you notice foul body odor in your private areas, you should change your underwear as well as wash up. (Strong odor there can also indicate an infection, such as bacterial vaginosis, which is the most common vaginal infection in women, has a fishy odor and requires antibiotics.)

So what do you do if you are in one of those situations where you don’t have any choice but to wear soiled underwear? Your next best choice may actually be to go commando — and next time, remember to throw some extra undies in your carry-on.

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