Acne begins to form under the surface of the skin in the hair follicle. At the bottom of the hair follicle is the sebaceous gland which makes an oily substance called sebum. Normally the sebum or oil produced by the sebaceous glands flows out of the hair follicle to the skin's surface. This oil carries with it dead skin cells from the follicle lining. During puberty, hormones called androgens stimulate increased oil production. Excess oil combines with dead skin cells, hair fragments, and bacteria to form plugs under the skin. These plugs are called comedones. They block the pores and prevent drainage of the oil mixture to the surface of the skin. When a plug forms under the skin it can be pushed to the surface and appear as a blackhead. If the plug does not reach the skin's surface and continues to grow, it can break the follicle wall and discharge its contents into the surrounding skin, causing a minor infection. The body responds to this infection by stimulating an immune response where white blood cells are sent to the infected area to fight the bacteria. This battle results in a whitehead.
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Benzoyl peroxideworks to prevent the formation of new pimples in two ways: by fighting infection with an antibiotic and by drying the skin. Drying the skin causes peeling which helps to unplug oil ducts and allows oil to escape. Begin by using the lowest strength (5% benzoyl peroxide).
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