Acne is a disease that affects the skin's oil glands. The small holes in your skin (pores) connect to oil glands under the skin. These glands make an oily substance called sebum. The pores connect to the glands by a canal called a follicle. Inside the follicles, oil carries dead skin cells to the surface of the skin. A thin hair also grows through the follicle and out to the skin. When the follicle of a skin gland clogs up, a pimple grows.

Most pimples are found on the face, neck, back, chest, and shoulders. Acne is not a serious health threat but, it can cause scars.

How Does Acne Develop?

Sometimes, the hair, sebum, and skin cells clump together into a plug. The bacteria in the plug causes swelling. Then when the plug starts to break down, a pimple grows.

There are many types of pimples. The most common types are:

• Whiteheads. These are pimples that stay under the surface of the skin.

• Blackheads. These pimples rise to the skin's surface and look black. The black color is not from dirt.

• Papules. These are small pink bumps that can be tender.

• Pustules. These pimples are red at the bottom and have pus on top.

• Nodules. These are large, painful, solid pimples that are deep in the skin.

• Cysts. These deep, painful, pus-filled pimples can cause scars.

Who Gets Acne?

Acne is the most common skin disease. Nearly 17 million people in the United States have it. People of all races and ages get acne. But it is most common in teenagers and young adults. Nearly 85 percent of people between the ages of 12 and 24 get acne. For most people, acne goes away by age 30. But some people in their forties and fifties still get acne.

What Causes Acne?

The cause of acne is unknown. Doctors think certain factors might cause it:

• The hormone increase in teenage years (this can cause the oil glands to plug up more often)

• Hormone changes during pregnancy

• Starting or stopping birth control pills

• Heredity (if your parents had acne, you might get it, too)

• Some types of medicine

• Greasy makeup.

How Is Acne Treated?

Acne is treated by doctors who work with skin problems (dermatologists). Treatment tries to:

• Heal pimples

• Stop new pimples from forming

• Prevent scarring

• Help reduce the embarrassment of having acne.

Early treatment is the best way to prevent scars. Your doctor may suggest over-the-counter (OTC) or prescription drugs. Some acne medicines are put right on the skin. Other medicines are pills that you swallow. The doctor may tell you to use more than one medicine.

How Should People With Acne Care for Their Skin?

Here are some ways to care for skin if you have acne:

• Clean skin gently. Use a mild cleanser in the morning, evening, and after heavy workouts. Scrubbing the skin does not stop acne. It can even make the problem worse.

• Try not to touch your skin. People who squeeze, pinch, or pick their pimples can get scars or dark spots on their skin.

• Shave carefully. If you shave, you can try both electric and safety razors. With safety razors, use a sharp blade. Also, it helps to soften your beard with soap and water before putting on shaving cream. Shave lightly and only when you have to.

• Stay out of the sun. Many acne drugs can make people more likely to sunburn. Being in the sun a lot can also make skin wrinkle and raise the risk of skin cancer.

• Choose makeup carefully. All makeup should be oil free. Look for the word "noncomedogenic" on the label. This means that the makeup will not clog up your pores. But some people still get acne even if they use these products.

What Things Can Make Acne Worse?

Some things can make acne worse:

• Changing hormone levels in teenage girls and adult women 2 to 7 days before their period starts

• Leaning on or rubbing the skin

• Pressure from bike helmets, backpacks, or tight collars

• Pollution and high humidity

• Squeezing or picking at pimples

• Hard scrubbing of the skin.

What Are Some Myths About the Causes of Acne?

There are many myths about what causes acne. Dirty skin and stress do not cause acne. Also, chocolate and greasy foods do not cause acne in most people.

What Research Is Being Done on Acne?

Scientists are looking at new ways to treat acne. They are:

• Working on new drugs to treat acne

• Looking at ways to prevent plugs

• Looking at ways to stop the hormone testosterone from causing acne.