The term “acne” refers to what is commonly known as pimples, zits or plugged pores. While most suffer from acne in their teenage years, a growing number of adults experience breakouts.  80 % of the population has acne in one form or another.
The most common lesion (pimple) is known as the microcomedone , where the hair follicle is plugged with P.acnes bacteria and sebum. The variations on this lesion are whitehead (comedos that stay below the surface) and blackheads (comedos which rise to the surface of the skin).  Another form of acne, found in people with dry skin, is called “asphyxiated acne”. This occurs when the top of the skin is extremely dry, upsetting the balance of the skin. Sebaceous glands then compensate for this dryness by overproducing sebum beneath the skin.

Causes

It is believed that acne is caused by cells from the hair follicle, which are shed too quickly. These cells eventually clump together and form a plug at the follicle’s opening, sebum from the sebaceous glands reaching the surface of the skin. The mixture of cells and oil feed the P.acnes bacteria in the plugged follicles, causing inflammation or swelling, redness, heat and pain .
While hormones, specifically Androgens, are the cause of acne in most people, factors such as genetics, the use of certain drugs (birth control, androgens, lithium and barbiturates), stress, friction, environmental pollutants and picking at blemishes can contribute to this condition.
The androgen testosterone regulates the amount of sebum produced by the sebaceous glands. It has been found that people with acne produce higher amounts of sebum and are likely sensitive to hormones.