Cutaneous larva migrans

Definition

Itching is an intense, distracting irritation or tickling sensation that may be felt all over the skin's surface, or confined to just one area. The medical term for itching is "pruritus."

Description

Itching instinctively leads most people to scratch the affected area. Different people can tolerate different amounts of itching, and anyone's threshold of tolerance can be changed due to stress, emotions, and other factors. In general, itching is more severe if the skin is warm, and if there are few distractions. This is why people tend to notice itching more at night.

Causes & symptoms

The reason for the sensation of itching is not well understood. While itching is the most noticeable symptom in many skin diseases, but it doesn't necessary mean that a person who feels itchy has a disease.

Stress and emotional upset can make itching worse, no matter what the underlying cause. If emotional problems are the primary reason for the itch, the condition is known as psychogenic itching. Some people become convinced that their itch is caused by a parasite; this conviction is often linked to burning sensations in the tongue, and may be caused by a major psychiatric disorder.

Generalized itching

Itching that occurs all over the body may indicate a medical condition such as diabetes mellitus, liver disease, kidney failure, jaundice, thyroid disorders (and rarely, cancer). Blood disorders such as leukemia, and lymphatic conditions such as Hodgkin's disease may sometimes cause itching as well.

Some people may develop an itch without a rash when they take certain drugs (such as aspirin, codeine, cocaine); others may develop an itchy red "drug rash" or hives because of an allergy to a specific drug.

Itching also may be caused when any of the family of hookworm larvae penetrate the skin. This includes swimmer's itch and creeping eruption caused by cat or dog hookworm, and ground itch caused by the "true" hookworm.

Many skin conditions cause an itchy rash. These include:

• Atopic dermatitis
• Chickenpox
• Contact dermatitis
• Dermatitis herpetiformis (occasionally)
• Eczema
• Fungus infections (such as athlete's foot)
• Hives (urticaria)
• Insect bites
• Lice
• Lichen planus
• Neurodermatitis (lichen simplex chronicus)
• Psoriasis (occasionally)
• Scabies.

On the other hand, itching all over the body can be caused by something as simple as bathing too often, which removes the skins natural oils and may make the skin too dry and scaly.

Localized itching

Specific itchy areas may occur if a person comes in contact with soap, detergents, and wool or other rough-textured, scratchy material. Adults who have hemorrhoids, anal fissure, or persistent diarrhea may notice itching around the anus (called "pruritus ani"). In children, itching in this area is most likely due to worms.

Intense itching in the external genitalia in women ("pruritus vulvae") may be due to candidiasis, hormonal changes, or the use of certain spermicides or vaginal suppositories, ointments, or deodorants.

It's also common for older people to suffer from dry, itchy skin (especially on the back) for no obvious reason. Younger people also may notice dry, itchy skin in cold weather. Itching is also a common complaint during pregnancy.

Diagnosis

Itching is a symptom that is quite obvious to its victim. Someone who itches all over should seek medical care. Because itching can be caused by such a wide variety of triggers, a complete physical exam and medical history will help diagnose the underlying problem. A variety of blood and stool tests may help determine the underlying cause.

Treatment

Antihistamines such as diphenhydramine (Benadryl) can help relieve itching caused by hives, but won't affect itching from other causes. Most antihistamines also make people sleepy, which can help patients sleep who would otherwise be awake from the itch.

Specific treatment of itching depends on the underlying condition that causes it. In general, itchy skin should be treated very gently. While scratching may temporarily ease the itch, in the long run scratching just makes it worse. In addition, scratching can lead to an endless cycle of itch--scratch--more itching.

To avoid the urge to scratch, a person can apply a cooling or soothing lotion or cold compress when the urge to scratch occurs. Soaps are often irritating to the skin, and can make an itch worse; they should be avoided, or used only when necessary.

Creams or ointments containing cortisone may help control the itch from insect bites, contact dermatitis or eczema. Cortisone cream should not be applied to the face unless a doctor prescribes it.

Probably the most common cause of itching is dry skin. There are a number of simple things a person can do to ease the annoying itch:

• Don't wear tight clothes
• Avoid synthetic fabrics
• Don't take long baths
• Wash the area in lukewarm water with a little baking soda
• For generalized itching, take a lukewarm shower
• Try a lukewarm oatmeal (or Aveeno) bath for generalized itching
• Apply bath oil or lotion (without added colors or scents) right after bathing.

People who itch as a result of mental problems or stress should seek help from a mental health expert.

Prognosis

Most cases of itching go away when the underlying cause is treated successfully.

Prevention

There are certain things people can do to avoid itchy skin. Patients who tend toward itchy skin should:

• Avoid a daily bath
• Use only lukewarm water when bathing
• Use only gentle soap
• Pat dry, not rub dry, after bathing, leaving a bit of water on the skin
• Apply a moisture-holding ointment or cream after the bath
• Use a humidifier in the home.

Patients who are allergic to certain substances, medications, and so on can avoid the resulting itch if they avoid contact with the allergen. Avoiding insect bites, bee stings, poison ivy and so on can prevent the resulting itch. Treating sensitive skin carefully, avoiding overdrying of the skin, and protecting against diseases that cause itchy rashes are all good ways to avoid itching.

Key Terms

Atopic dermatitis

An intensely itchy inflammation often found on the face of people prone to allergies. In infants and early childhood, it's called infantile eczema.

Creeping eruption

Itchy irregular, wandering red lines on the foot made by burrowing larvae of the hookworm family and some roundworms.

Dermatitis herpetiformis

A chronic very itchy skin disease with groups of red lesions that leave spots behind when they heal. It is sometimes associated with cancer of an internal organ.

Eczema

A superficial type of inflammation of the skin that may be very itchy and weeping in the early stages; later, the affected skin becomes crusted, scaly, and thick. There is no known cause.

Hodgkin's disease

A type of cancer characterized by a slowly-enlarging lymph tissue; symptoms include generalized itching.

Lichen planus

A noncancerous, chronic itchy skin disease that causes small, flat purple plaques on wrists, forearm, ankles.

Neurodermatitis

An itchy skin disease (also called lichen simplex chronicus) found in nervous, anxious people.

Psoriasis

A common, chronic skin disorder that causes red patches anywhere on the body. Occasionally, the lesions may itch.

Scabies

A contagious parasitic skin disease characterized by intense itching.

Swimmer's itch

An allergic skin inflammation caused by a sensitivity to flatworms that die under the skin, causing an itchy rash.

Further Reading

For Your Information

Books

• Donahue, Peggy Jo. Relief from Chronic Skin Problems. New York: Dell Publishing, 1992.
• Olbricht, Suzanne, Michael Bigby, and Kenneth Arndt. Manual of Clinical Problems in Dermatology. Boston: Little, Brown, 1992.
• Turkington, Carol A., and Jeffrey S. Dover. Skin Deep: An A to Z of Skin Disorders, Treatments and Health. New York: Facts on File, 1998.

  Periodicals

• Bogin, Rob. "Don't Scratch That Itch." Rocky Mountain News (Oct. 5, 1997): 6F.

Gale Encyclopedia of Medicine. Gale Research, 1999.