Frequently Asked Questions About Acne

What Is Acne?

Acne is a disorder resulting from the action of hormones and other substances on the skin's oil glands (sebaceous glands) and hair follicles. These factors lead to plugged pores and outbreaks of lesions commonly called pimples or zits. Acne lesions usually occur on the face, neck, back, chest, and shoulders. Although acne is usually not a serious health threat, it can be a source of significant emotional distress. Severe acne can lead to permanent scarring.

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). 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

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 an open comedo or blackhead because it looks black on the skin's surface. This black discoloration is due to changes in sebum as it is exposed to air. It is not due to dirt. Both whiteheads and blackheads may stay in the skin for a long time.

Types of Lesions

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 white or yellow 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?

The exact cause of acne is unknown, but doctors believe it results from several related factors. One important factor is an increase in hormones called androgens (male sex hormones). These increase in both boys and girls during puberty and cause the sebaceous glands to enlarge and make more sebum. Hormonal changes related to pregnancy or starting or stopping birth control pills can also cause acne.

Another factor is heredity or genetics. Researchers believe that the tendency to develop acne can be inherited from parents. For example, studies have shown that many school-age boys with acne have a family history of the disorder. Certain drugs, including androgens and lithium, are known to cause acne. Greasy cosmetics may alter the cells of the follicles and make them stick together, producing a plug.

Factors That Can Make Acne Worse

Factors that can cause an acne flare include:

  • Changing hormone levels in adolescent girls and adult women 2 to 7 days before their menstrual period starts
  • Oil from skin products (lubricants or cosmetics) or grease encountered in the work environment (for example, a kitchen with fry vats)
  • Pressure from sports helmets or equipment, backpacks, tight collars, or tight sports uniforms
  • Environmental irritants, such as pollution and high humidity
  • Squeezing or picking at blemishes
  • Hard scrubbing of the skin
  • Stress.

Myths About the Causes of Acne

There are many myths about what causes acne. Chocolate and greasy foods are often blamed, but there is little evidence that foods have much effect on the development and course of acne in most people. Another common myth is that dirty skin causes acne; however, blackheads and other acne lesions are not caused by dirt. Stress doesn't cause acne, but research suggests that for people who have acne, stress can make it worse.

Who Gets Acne?

People of all races and ages get acne. It is most common in adolescents and young adults. An estimated 80 percent of all people between the ages of 11 and 30 have acne outbreaks at some point. For most people, acne tends to go away by the time they reach their thirties; however, some people in their forties and fifties continue to have this skin problem.

How Is Acne Treated?

Acne is often treated by dermatologists (doctors who specialize in skin problems). These doctors treat all kinds of acne, particularly severe cases. Doctors who are general or family practitioners, pediatricians, or internists may treat patients with milder cases of acne.

The goals of treatment are to heal existing lesions, stop new lesions from forming, prevent scarring, and minimize the psychological stress and embarrassment caused by this disease.

Treatment for Blackheads, Whiteheads, and Mild Inflammatory Acne

Doctors usually recommend an OTC or prescription topical medicine for people with mild signs of acne. Topical medicine is applied directly to the acne lesions or to the entire area of affected skin.

There are several OTC topical medicines used for mild acne. Each works a little differently. Following are the most common ones:

  • Benzoyl peroxide—destroys P. acnes, and may also reduce oil production
  • Resorcinol—can help break down blackheads and whiteheads
  • Salicylic acid—helps break down blackheads and whiteheads. Also helps cut down the shedding of cells lining the hair follicles
  • Sulfur—helps break down blackheads and whiteheads.

Topical OTC medicines are available in many forms, such as gels, lotions, creams, soaps, or pads. In some people, OTC acne medicines may cause side effects such as skin irritation, burning, or redness, which often get better or go away with continued use of the medicine. If you experience severe or prolonged side effects, you should report them to your doctor.

OTC topical medicines are somewhat effective in treating acne when used regularly; however, it may take up to 8 weeks before you see noticeable improvement.

How Should People With Acne Care for Their Skin?

Clean Skin Gently

If you have acne, you should gently wash your face with a mild cleanser, once in the morning and once in the evening, as well as after heavy exercise. Wash your face from under the jaw to the hairline and be sure to thoroughly rinse your skin.

Ask your doctor or another health professional for advice on the best type of cleanser to use.

Using strong soaps or rough scrub pads is not helpful and can actually make the problem worse. Astringents are not recommended unless the skin is very oily, and then they should be used only on oily spots.

It is also important to shampoo your hair regularly. If you have oily hair, you may want to wash it every day.

Avoid Frequent Handling of the Skin

Avoid rubbing and touching skin lesions. Squeezing, pinching or picking blemishes can lead to the development of scars or dark blotches.

Shave Carefully

Men who shave and who have acne should test both electric and safety razors to see which is more comfortable. When using a safety razor, make sure the blade is sharp and soften your beard thoroughly with soap and water before applying shaving cream. Shave gently and only when necessary to reduce the risk of nicking blemishes.

Avoid a Sunburn or Suntan

Many of the medicines used to treat acne can make you more prone to sunburn. A sunburn that reddens the skin or suntan that darkens the skin may make blemishes less visible and make the skin feel drier. However, these benefits are only temporary, and there are known risks of excessive sun exposure, such as more rapid skin aging and a risk of developing skin cancer.

Choose Cosmetics Carefully

While undergoing acne treatment, you may need to change some of the cosmetics you use. All cosmetics, such as foundation, blush, eye shadow, lubricants, and hair-care products should be oil free. Choose products labeled noncomedogenic (meaning they don't promote the formation of closed pores). In some people, however, even these products may make acne worse.

NIH Publication No. 06-4998