Common among teenagers, acne can strike adults into their 30s and 40s, appearing on the arms, legs, chest, back and buttocks as well as the face and shoulders. Causes include the hormone changes of pregnancy, stress and menopause; prescription drugs such as steroids, estrogen and testosterone; certain cosmetics; high humidity; and sweating.

    Washing your skin with a gentle cleanser twice daily, especially after exercising; avoiding touching your face; and using water-based cosmetics or creams can reduce blemishes. Over-the-counter medications with benzoyl peroxide, salicylic acid, sulfur or resorcinol also can help by killing bacteria and exfoliating the skin. A dermatologist can prescribe stronger medication if needed.