What causes acne?

Hormones, diet?: Androgens ("male hormones" such as testosterone) are clearly implicated in causing acne. There is good circumstantial evidence that high glycemic index diet plays a role, too. Hunter/gatherer people rarely have problems with acne until adopting high glycemic index "western" diets. Hormones in dairy may be another source.

Acne cause(s): The three major factors that contribute to acne formation include irregular shedding of surface skin cells that clog and inflame pores, overproduction of sebum that mixes with dead skin cells to form a soft plug in hair follicles/pores and bacterial build up. Androgens, pregnancy-related hormonal changes, some medications can worsen acne. Certain foods have been implicated in aggravating acne.