Wearing the same underwear two days in a row may seem harmless, but dermatologists warn it can cause irritation, odor, and infections. “Underwear sits directly against your most sensitive and moisture-prone areas,” collecting sweat, oils, and bacteria. Rewearing it reintroduces these to your skin, especially with added warmth and moisture.

Regularly repeating can lead to bacterial infections like UTIs, jock itch, and folliculitis, as well as yeast overgrowth, rashes, and even acne on the thighs or buttocks. “Moisture + heat + tight clothing = the perfect storm for yeast.” Odor also develops as bacteria break down sweat and oils.

While a low-risk day at home in loose, clean cotton might be safe occasionally, risks rise after sweating or wearing synthetics, which trap heat and bacteria. Cotton is best for daily use, while lace, silk, and synthetics should be worn briefly. Women are more prone to infections, while men face higher risks of chafing and jock itch.

Experts also suggest skipping underwear at night to let skin breathe. If you must rewear, air them out and ensure they’re dry — but avoid it after exercise.

Bottom line: “It’s not ideal.” Clean underwear daily protects your skin, health, and confidence.