When the follicle of an oil gland becomes clogged with oil, skin cells, and bacteria, it's called a pimple. Several pimples occurring in the same area are known as acne. Nearly 17 million people in the United States have this condition, making it the most common skin disease. Heredity, changing hormone levels, and even some types of medicine and makeup can contribute to it. Fortunately, almost every case can be resolved with proper treatment. In some cases, it can even be prevented.
What Is Acne?
Acne is a disease that affects the skin's oil glands. The tiny holes in your skin (pores) connect to oil glands under the skin through a canal called a follicle. Inside the follicles, sebum (an oily substance the glands produce) carries dead skin cells to the surface of the skin. A thin hair also grows through the follicle and out to the skin. When a follicle gets clogged up with cells and sebum, a pimple develops.
Most pimples (also known as zits) are found on the:
The term "acne" simply refers to several pimples occurring together. Nearly 17 million people in the United States have acne, making it the most common skin disease. Although it is not a serious health threat, severe acne can lead to disfiguring, permanent scarring. This can be upsetting to people who are affected by the disorder.
Doctors describe acne as a disease of the pilosebaceous units (PSUs). Found over most of the body, PSUs consist of a sebaceous (oil) gland connected to a canal -- called a follicle -- that contains a fine hair. 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's surface through the opening of the follicle, commonly called a pore. Cells called keratinocytes line the follicle.
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 that normally live on the skin to grow inside the plugged follicles. These bacteria, known as Propionibacterium acnes (P. acnes), 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.