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Oil production in the sebaceous glands increases during puberty, causing comedones and acne to be common in adolescents.[3][4] Acne is also found premenstrually and in women with polycystic ovarian syndrome.[3] Smoking may worsen acne.[3]
Oxidation rather than poor hygiene or dirt causes blackheads to be black.[2] Washing or scrubbing the skin too much could make it worse, by irritating the skin.[2] Touching and picking at comedones might cause irritation and spread infection.[2] What effect shaving has on the development of comedones or acne is unclear.[2]
Some skin products might increase comedones by blocking pores,[2] and greasy hair products (such as pomades) can worsen acne.[3] Skin products that claim to not clog pores may be labeled noncomedogenic or nonacnegenic.[6] Make-up and skin products that are oil-free and water-based may be less likely to cause acne.[6] Whether dietary factors or sun exposure make comedones better, worse, or neither is unknown.[3]
A hair that does not emerge normally, an ingrown hair, can also block the pore and cause a bulge or lead to infection (causing inflammation and pus).[4]
Genes may play a role in the chances of developing acne.[3] Comedones may be more common in some ethnic groups.[3][7] People of Latino and recent African descent may experience more inflammation in comedones, more comedonal acne, and earlier onset of inflammation.[3][7]
