Underwear isn’t just fabric; it’s the front line between your skin, your genitals, and everything your body sheds in a day. Dermatologists agree that context matters: light activity in a cool climate, loose cotton boxers, and a clean body might allow a man to push wear closer to 48 hours without serious harm. But once sweat, heat, tight synthetic fabrics, or friction enter the picture, that window slams shut. Moisture and warmth create a breeding ground for bacteria and yeast, turning stretched-out habits into itching, burning, and infections.

Women carry the heavier risk. A shorter urethra, folds of the vulva, menstrual blood, and discharge all mean bacteria and fungi have easier access and more places to hide. For many women, daily changes are non‑negotiable, and during heavy periods, intense workouts, or hot, humid days, changing more than once is often the safest, most comfortable choice. In the end, experts say the rule is simple: listen to your body, respect moisture and discomfort as warning signs, and treat clean underwear not as a chore, but as quiet, daily protection for your health.