These changes are brought on primarily by rising levels of sex hormones in the body. Both boys and girls experience an increase in the levels of hormones called androgens that increase the size of the sebaceous glands, promote the production of sebum, and contribute to acne. Androgens are not the only hormones that promote sebum production and influence the development of acne. Progesterone, a female hormone produced by the ovary after the egg is released, can increase acne immediately before menstruation. Some doctors believe that teenage skin is immature and that the pores, or openings in the skin follicles, are not as wide as they will become in adulthood.
Bacteria are another contributing factor to acne.
Although these tiny organisms do not cause infection themselves, they may play an indirect role by changing the chemical nature of sebum or by causing the follicle wall to rupture more easily to produce inflammation. Drugs and Industrial chemicals. Acne-like conditions may also result from the use of certain drugs, primarily bromides, iodides, corticosteroids, androgens, and drugs used to treat epilepsy. Industrial substances, including coal tar and petroleum oil, may also cause severe cases of acne. Pressure on the skin from clothing, backpacks, football shoulder pads, headbands, sport masks and helmets can aggravate acne by friction.