Acne is the most common skin disease treated by physicians. Acne can appear at any age, although there are peaks of incidence in adolescence and again for females near the time of menopause.
Acne and adolescence are so closely associated that 80–90% of all teenagers have at least some lesions at any given time.
It is important to note that acne is not caused by dirty skin, vigorous washing may cause more inflammation and induce progression of lesions. The visible black part of the blackhead is not dirt it is melanin and oxidized material, this cannot be removed by washing either.