Acne Help Facts Sheets
Questions and Answers About Acne
This fact sheet contains general information about acne.
It describes what acne is and how it develops, the causes of acne, and
the treatment options for various forms of acne. Information is also
provided on caring for the skin. If you have further questions after
reading this booklet, you may wish to discuss them with your doctor.
What Is Acne?
Acne is a disorder resulting from the action of hormones
on the skin's oil glands (sebaceous glands), which leads to plugged
pores and outbreaks of lesions commonly called pimples or zits. Acne
lesions usually occur on the face, neck, back, chest, and shoulders.
Nearly 17 million people in the United States have acne, making it the
most common skin disease. Although acne is not a serious health threat,
severe acne can lead to disfiguring, permanent scarring, which can be
upsetting to people who are affected by the disorder.
How Does Acne Develop?
Doctors describe acne as a disease of the pilosebaceous
units (PSUs). Found over most of the body, PSUs consist of a sebaceous
gland connected to a canal, called a follicle, that contains a fine
hair (see "Normal Pilosebaceous Unit" diagram, below). These units are
most numerous on the face, upper back, and chest. The sebaceous glands
make an oily substance called sebum that normally empties onto the skin
surface through the opening of the follicle, commonly called a pore.
Cells called keratinocytes line the follicle.
| Normal Pilosebaceous Unit |
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The hair, sebum, and keratinocytes that fill the narrow
follicle may produce a plug, which is an early sign of acne. The plug
prevents sebum from reaching the surface of the skin through a pore.
The mixture of oil and cells allows bacteria Propionibacterium acnes
(P. acnes) that normally live on the skin to grow in the plugged
follicles. These bacteria produce chemicals and enzymes and attract
white blood cells that cause inflammation. (Inflammation is a characteristic
reaction of tissues to disease or injury and is marked by four signs:
swelling, redness, heat, and pain.) When the wall of the plugged follicle
breaks down, it spills everything into the nearby skin--sebum, shed
skin cells, and bacteria--leading to lesions or pimples.
People with acne frequently have a variety of lesions,
some of which are shown in the diagrams below. The basic acne lesion,
called the comedo (KOM-e-do), is simply an enlarged and plugged hair
follicle. If the plugged follicle, or comedo, stays beneath the skin,
it is called a closed comedo and produces a white bump called a whitehead.
A comedo that reaches the surface of the skin and opens up is called
a blackhead because it looks black on the skin's surface. This black
discoloration is not due to dirt. Both whiteheads and blackheads may
stay in the skin for a long time.
Other troublesome acne lesions can develop, including
the following:
- Papules--inflamed lesions that usually appear as small, pink
bumps on the skin and can be tender to the touch
- Pustules (pimples)--papules topped by pus-filled lesions
that may be red at the base
- Nodules--large, painful, solid lesions that are lodged deep
within the skin
- Cysts--deep, painful, pus-filled lesions that can cause scarring.
What Causes Acne?
Who Gets Acne?
How Is Acne Treated?
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