Intertrigo. Close-up of an intertrigo rash under a woman's breast. The underside of the breast is mostly red, and the skin below is dotted with spots resembling pustules. Intertrigo is an infla- mmation caused by warm, sweaty folds of skin rub- bing repeatedly together. The affected area may blister and become odorous, and is sometimes aggravated by infection. Intertrigo is most common in the obese or elderly, and usually occurs on the thighs, armpits, breasts, folds of the abdomen, or between the fingers. Treatment includes weight reduction & keeping affected areas as clean & dry as possible. Drugs may be needed if there is severe inflammation or fungal infection.