Three factors contribute to the formation of acne:
Overproduction of oil (sebum)
Irregular shedding of dead skin cells resulting in irritation of the hair follicles of your skin
Buildup of bacteria
Acne occurs when the hair follicles become plugged with oil and dead skin cells. Hair follicles are connected to sebaceous glands. These glands secrete an oily substance known as sebum to lubricate your hair and skin. Sebum normally travels up along the hair shafts and then out through the openings of the hair follicles onto the surface of your skin. When your body produces an excess amount of sebum and dead skin cells, the two can build up in the hair follicles and form together as a soft plug, creating an environment where bacteria can thrive.
This plug may cause the follicle wall to bulge and produce a whitehead. Or, the plug may be open to the surface and may darken, causing a blackhead. Pimples are raised red spots with a white center that develop when blocked hair follicles become inflamed or infected. Blockages and inflammation that develop deep inside hair follicles produce lumps beneath the surface of your skin called cysts. Other pores in your skin, which are the openings of the sweat glands onto your skin, aren’t normally involved in acne.
Factors that may worsen acne
These factors can trigger or aggravate an existing case of acne:
Hormones. Androgens are hormones that increase in boys and girls during puberty and cause the sebaceous glands to enlarge and make more sebum. Hormonal changes related to pregnancy and the use of oral contraceptives can also affect sebum production.
Certain medications. Drugs containing corticosteroids, androgens or lithium are known to cause acne.
Diet. Studies indicate that certain dietary factors, including dairy products and carbohydrate-rich foods — such as bread, bagels and chips, which increase blood sugar — may trigger acne.
Contrary to what some people think, these factors have little effect on acne:
Greasy foods and chocolate have proved to have little to no effect on the development or course of acne.
Dirty skin. Acne isn’t caused by dirt. In fact, scrubbing the skin too hard or cleansing with harsh soaps or chemicals irritates the skin and can make acne worse. Simple cleansing of the skin to remove excess oil and dead skin cells is all that’s required.