It is a thick white oily substance. There are excessive numbers of cells that slough off the walls of the follicles. The sloughed cells can obstruct the opening or outlet of the follicle and result in an inflamed lesion called a comedo. Many times these inflamed lesions will become infected with bacteria called Propionibacterium Acnes. This bacteria results in an inflammatory reaction which may cause increasing redness and swelling of the acne lesion.
Acne tends to begin during or right before puberty.
This is because puberty is characterized by an increase in sex hormones. These hormones cause development of secondary sex characteristics in both males and females. Persons who get severe acne do not necessarily have an over production of hormones, but rather a hyperresponse to the hormones. It is usually not red or inflamed. Lesions occur on the central forehead, chin, and nose.