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NIH MedlinePlus the Magazine, Trusted Health Information from the National Institutes of Health


Skin Health and Skin Diseases

A woman in a hat.

Everyone needs protection from the sun.
Photo: PhotoDisc

Care for conditions from acne to wrinkles

Did you know that your skin is the largest organ of your body? It is, in terms of both weight—between 6 and 9 pounds—and surface area—about 2 square yards. Your skin separates the inside of your body from the outside world. It protects you from bacteria and viruses, and regulates your body temperature.

Conditions that irritate, clog, or inflame your skin can cause symptoms such as redness, swelling, burning, and itching. Allergies, irritants, your genetic makeup, and certain diseases and immune system problems can cause dermatitis, hives, and other skin conditions. Many skin problems, such as acne, also affect your appearance. Your skin can also develop several kinds of cancers.

Here are the key facts about some of the most common skin problems:

Acne—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 a substance called sebum. The pores connect to the glands by a canal called a follicle. When the follicle of a skin gland clogs up, a pimple grows. Acne is the most common skin disease; an estimated 80 percent of all people have acne at some point. Early treatment is the best way to prevent scars. Your doctor may suggest over-the-counter (OTC) or prescription drugs.

A child's face with Eczema

© 2008 Logical Images, Inc.

Eczema—Also known as atopic dermatitis, this is a long-term skin disease. The most common symptoms are dry and itchy skin, rashes on the face, inside the elbows, behind the knees, and on the hands and feet. Currently, there is no single test to diagnose eczema, so doctors rely on information about you and your family.

Hives—Red and sometimes itchy bumps on your skin. An allergic reaction to a drug or food usually causes them. People who have other allergies are more likely to get hives than other people. Other causes include infections and stress. Hives are very common. They usually go away on their own, but if you have a serious case, you might need medical help.

Impetigo—A skin infection caused by bacteria. Usually the cause is staphylococcal (staph), but sometimes streptococcus (strep) can cause it, too. It is most common in children between the ages of 2 and 6. It usually starts when bacteria get into a break in the skin, such as a cut, scratch, or insect bite. Symptoms start with red or pimple-like sores surrounded by red skin. These sores usually occur on your face, arms, and legs. The sores fill with pus, then break open after a few days and form a thick crust. You can treat impetigo with antibiotics.

A Photo of Melanoma

© 2008 Logical Images, Inc.

Melanoma—A severe and potentially life-threatening skin cancer. The "ABCD's" of what to watch for with the moles on your skin:

  • Asymmetry: the shape of one half does not match the other
  • Border: the edges are ragged, blurred, or irregular
  • Color: the color is uneven and may include shades of black, brown, and tan
  • Diameter: there is a change in size, usually an increase

People with melanoma may have surgery, chemotherapy, biological therapy, radiation therapy, or a combination of those.

To Find Out More

  • Skin cancer is the most common form of cancer in the United States. The two most common types are basal cell cancer and squamous cell cancer. Melanoma, a more serious type of skin cancer, is less common.
  • The number of cases of skin cancer has been increasing. Exposure to the sun is a major factor.
  • In 2006, over 30 million people visited health-care providers for skin rashes.

Moles—Growths on the skin. They happen when cells in the skin, called melanocytes, grow in a cluster with tissue surrounding them. Most people have between 10 and 40 moles. A person may develop new moles from time to time, usually until about age 40. About one out of every 10 people has at least one unusual (or atypical) mole that looks different from an ordinary mole. They may be more likely than ordinary moles to develop into melanoma, a type of skin cancer. Because of this, you should have a health care professional check your moles if they look unusual, grow larger, change in color or outline, or in any other way.

A Photo of an arm with Psoriasis

© 2008 Logical Images, Inc.

Psoriasis—A skin disease that causes scaling and swelling. Most psoriasis causes patches of thick, red skin with silvery scales. These patches can itch or feel sore. They are often found on the elbows, knees, other parts of the legs, scalp, lower back, face, palms, and soles of the feet. But they can show up on other areas, as well. Psoriasis can be hard to diagnose because it can look like other skin diseases. The doctor might need to look at a small skin sample under a microscope. Treatment depends on how serious the disease is, the size of the psoriasis patches, the type of psoriasis, and how the patient reacts to certain treatments.

Rashes (basic dermatitis)—Dry and itchy skin; Rashes on the face, inside the elbows, behind the knees, and on the hands and feet. Your doctor will help you develop a good skin care routine, learn to avoid things that lead to flares, and treat symptoms when they occur.

A Photo of a mans face with Rosacea

© 2008 Logical Images, Inc.

Rosacea— Frequent redness (flushing) of the face; small red lines under the skin; inflamed eyes/eyelids, a swollen nose, and thicker skin. Your physician can usually diagnose rosacea with a thorough medical history and physical exam. There is no cure for rosacea, but it can be treated and controlled.

Skin Cancer—Skin cancer is the most common form of cancer in the United States. The two most common types are basal cell cancer and squamous cell cancer. They usually form on the head, face, neck, hands, and arms. Another type of skin cancer, melanoma, is more dangerous but less common.

Wrinkles—Your skin changes as you age. You might notice wrinkles, age spots, and dryness. Sunlight is a major cause of skin aging. (See "Skin and Sun—Not a Good Mix"). Cigarette smoking also contributes to wrinkles. The wrinkling increases with the number of cigarettes and years a person has smoked. Many products claim to revitalize aging skin or reduce wrinkles, but the Food and Drug Administration has approved only a few for sun-damaged or aging skin. Various treatments soothe dry skin and reduce the appearance of age spots.

Skin images courtesy of VisualDxHealth (

Fall 2008 Issue: Volume 3 Number 4 Pages 22 - 25