By Erica Metzger
Why it happens: When your clothing traps sweat and oil -- because you were working out or bundled up in layers -- it can mix with dead skin and bacteria in your pores to form pimples.
The fix: Use a body wash with salicylic acid or benzoyl peroxide to kill bacteria and unclog pores. Dermatologist Jeannette Graf, MD, suggests applying an alphahydroxy peel three nights a week. "The acids help get rid of any lingering redness once the pimples are gone."