Acne is a common skin condition that happens when hair follicles under the skin become clogged. Sebum—oil that helps keep skin from drying out—and dead skin cells plug the pores, which leads to outbreaks of lesions, commonly called pimples or zits. Most often, the outbreaks occur on the face but can also appear on the back, chest, and shoulders.

Types of Acne

Acne causes several types of lesions, or pimples. Doctors refer to enlarged or plugged hair follicles as comedones. Types of acne include:

-Whiteheads: Plugged hair follicles that stay beneath the skin and produce a white bump.

-Blackheads: Plugged follicles that reach the surface of the skin and open up. They look black on the skin surface because the air discolors the sebum, not because they are dirty.

-Papules: Inflamed lesions that usually appear as small, pink bumps on the skin and can be tender to the touch.

-Pustules or pimples: Papules topped by white or yellow pus-filled lesions that may be red at the base.

-Nodules: Large, painful solid lesions that are lodged deep within the skin.

-Severe nodular acne (sometimes called cystic acne): Deep, painful, pus-filled lesions.