Acne appears usually on the parts where many sebaceous glands are, especially on the face, in the
pmiddle of the chest, upper part of the back, on the shoulders and around the neck. Some forms of acne affect the
arms and the legs as well. Most often acne appears in the puberty and very rarely before that. Since puberty starts
sooner for girls than it does for the boys, also acne occurs a bit sooner. When people are more than 21 years
old the number of black-heads and inflamed forms of acne starts to drop.