The main component, azelaic acid, works in two ways. It acts to reduce the growth of keratin surface skin cells. These surface cells can mix with sebum, which is a natural oily substance produced by the skin in the sebaceous glands. When keratin skin cells mix with sebum they can form a plug, blocking the pores on the skin.
Skinoren cream also kills the bacteria associated with acne (propionibacterium). This common bacteria feeds on the sebum produced by the skin. This feeding causes propionibacterium to produce waste products and fatty acids that irritate the sebaceous glands, causing them to become infected and inflamed and resulting in acne symptoms.
Azelaic acid also has the ability to lighten the skin by affecting melanin production, which is why some people use it to treat hyperpigmentation or dark underarm skin.