If the blocked follicle is closed at the surface, a closed comedo, or a whitehead forms. If the blocked follicle is exposed to air, it discolors, resulting in an open comedo, or a blackhead. This discoloration is not dirt, but skin pigments in the blocked follicle. Often the hair follicle wall bursts, spreading the sebum, bacteria, and dead cells to deeper layers of the skin, which, in turn, causes an inflammatory reaction, and the skin may redden and swell. When this happens, a papule, or pimple, forms.
Cocoa butter is a big offender.
Squeezing and picking a pimple may spread the acne and lead to scarring. Equipment worn during contact sports may also aggravate acne, as can hair worn over the forehead. Sleep loss, emotional pressure and overall stress may sometimes make acne worse for reasons that are also not known. Contrary to popular belief, food rarely causes acne. Eating chocolate, greasy foods, cola drinks, fish, milk products, etc., is seldom related to acne.