Acne is a common skin condition characterized by clogged hair follicles beneath the skin’s surface. When sebum—oil that prevents skin dryness—and dead skin cells block pores, it leads to outbreaks of lesions commonly known as pimples or zits. While acne primarily affects the face, it can also appear on the back, chest, and shoulders.

Acne is an inflammatory disorder of the skin, involving sebaceous (oil) glands connected to hair follicles, which contain fine hair. In healthy skin, sebaceous glands produce sebum that exits onto the skin surface through pores, small openings in the follicles. The follicles are lined with keratinocytes, a type of skin cell. Normally, as the body sheds skin cells, keratinocytes rise to the skin surface. In acne, however, hair, sebum, and keratinocytes become stuck inside the pore, preventing shedding and blocking sebum from reaching the skin surface. This mixture of oil and cells allows bacteria living on the skin to thrive in the clogged follicles, leading to inflammation—characterized by swelling, redness, heat, and pain. When the wall of the blocked follicle ruptures, it releases bacteria, skin cells, and sebum into nearby skin, resulting in lesions or pimples.

While acne typically resolves by one’s thirties, some individuals in their forties and fifties continue to experience this skin condition.