Chafing leaves the skin sore when body parts rub against each other (usually the thighs, upper arms and under the breasts) or when ill-fitting clothing rub against the skin. One way to avoid chafing is by wearing proper fitting clothes and undergarments that prevent friction. For those of us whose thighs rub together, exercising and eating well can help slim those thighs down and stop the problem. If chafing is bad, it may be a sign of a yeast infection in the area (they don't only happen in the vagina) that needs to be treated with an over-the-counter (OTC) topical anti-fungal medication. If the skin becomes infected, see your doctor who may prescribe antibiotics.