Conditions + Treatments

Acne Symptoms & Causes

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What is acne?

Acne is a chronic disorder of the hair follicles and sebaceous glands that appears in the form of pimples and cysts, which develop when the sebaceous glands are clogged.

Acne is very common and most often begins in puberty. During puberty, the male sex hormones, called androgens, increase in both boys and girls. This causes the sebaceous glands to become more active and results in the increased production of sebum.

What are sebaceous glands?

Sebaceous glands are located in the middle layer of skin, called the dermis, and secrete oil onto the skin.

How does acne develop?

The sebaceous glands produce oil, or sebum, which normally travels to the skin's surface via hair follicles. But when skin cells plug the follicles, blocking the oil coming from the sebaceous glands, skin bacteria (called Propionibacterium acnes, or P. acnes) begin to grow inside the follicles, causing inflammation.

Acne progresses in the following manner:

  • Incomplete blockage of the hair follicle results in blackheads (a semisolid, black plug).
  • Complete blockage of the hair follicle results in whiteheads (a semisolid, white plug).
  • Infection and irritation cause whiteheads to form.

Eventually, the plugged follicle bursts, spilling oil, skin cells and the bacteria onto the skin surface. In turn, the skin becomes irritated, and pimples or lesions begin to develop. The basic acne lesion is called a comedo.

Acne can be superficial, producing pimples without abscesses, or deep, producing inflamed pimples that push down into the skin and cause pus-filled cysts that rupture and result in larger abscesses.

What causes acne?

Rising hormone levels during puberty may cause acne. In addition, acne is often inherited. Other causes of acne may include the following:

  • hormone level changes during the menstrual cycle in women
  • certain drugs (such as corticosteroids, lithium, and barbiturates)
  • oil and grease from the scalp, mineral or cooking oil, and certain cosmetics
  • friction or pressure from helmets, backpacks, or tight collars
  • environmental conditions (such as pollution or humidity)

Contrary to popular belief, research has shown that eating chocolate or greasy food doesn't cause acne. Neither does dirty skin.       

Acne can also be aggravated by squeezing pimples or by scrubbing the skin too hard.

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