Formula Medical Group
Apple Valley, CA

James Krider, MD

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Rashes - exanthemas/skin lesions

A vast array of allergic reactions and diseases can cause rashes. Doctors generally refer to any skin eruption as a rash, even though rashes vary greatly in character and extent. Some rashes form blisters, while others produce red spots that turn purple or black. Some rashes are painful, and others are itchy or painless. Rashes may be localized, appearing only in a particular area, or they may spread all over the body.

Causes of rashes

A rash is often a symptom of an allergic reaction to food, animals, plants, chemicals, or numerous other substances present in the environment. It often takes the form of eczema, itchy red patches that form crusts and scales. Although eczema can cover the entire body, it is more often confined to specific areas, such as the creases of the arms, legs, and neck. Hives (urticaria) is an outbreak of itchy skin welts of varying sizes that may develop externally — on the face, lips, tongue, throat, eyes, and ears — or internally. Contact dermatitis is a rash that results from direct skin contact with many animal, plant, chemical, and mineral substances. It is often accompanied by blistering. Poison ivy is a familiar example of contact dermatitis, as is an allergic reaction to nickel.

Drug reactions
Itchy rashes and hives are often caused by a reaction to a drug. Penicillin, ampicillin, sulfa drugs, barbiturates, anticonvulsants, insulin, local anesthetics, and the contrast dyes used during some x-ray studies can all produce rashes in some people. Injections of gold salts, sometimes used to treat rheumatoid arthritis, may also lead to a rash. Even aspirin can cause hives, or make the

herpes fever blister

There are many different types of rashes.

There are many different types of rashes.

rash worse in a person who already has hives. Development of a drug-related rash should always be reported to the prescribing physician.

Infant rashes
A baby's skin is particularly susceptible to a variety of rashes. Most of these rashes are harmless, but they can make a baby uncomfortable. If the baby scratches them, there is a risk of infection.

Infectious diseases
Rashes often are a symptom of a number of infectious diseases, from familiar childhood ones such as chickenpox and measles to other, less common infections. The nature of the rash and other accompanying symptoms help to diagnose the specific infection.

Intestinal disorders
Crohn's disease and ulcerative colitis, both serious intestinal disorders, produce skin rashes in some patients.

Miliaria, better known as prickly heat, is an irritating, itchy rash brought on by sweating. It is more common in infants and children but may also affect adults.

Toxic shock syndrome
This serious and potentially fatal disease is a form of blood poisoning. It largely affects women and is often associated with the use of tampons. One of its symptoms is a red, peeling rash that resembles a sunburn.

Vitamin deficiencies and excesses
A deficiency of niacin, one of the B vitamins, is the principal cause of pellagra, a condition that is characterized by a rash and other skin symptoms. Vitamin C deficiency causes easy bleeding and red skin spots that turn purple. Excessive amounts of some vitamins, especially vitamin A, can also cause skin rashes.

This article was last reviewed November 12, 2005 by Dr. James Krider.
Reproduced in part with permission of Home Health Handbook.
Allergic reactions
Contact dermatitis
Cradle cap
Crohn's disease
Diaper rash
Eczema, chronic
Kawasaki's disease
Localized dermatitis
Med's, antibiotics
Med's, arthritis
Med's, asthma
Med's, diabetes
Med's, heart
Med's, painkillers
Med's, skin
Med's, tranquilizers
Poison ivy/oak/sumac
Prickly heat
Rheumatic fever
Rocky mountain fever
Scarlet fever
Sun sensitivity
Toxic shock syndrome
Typhoid fever
Ulcerative colitis
Vitamin B complex
Vitamin C
Vit's, megadose
Vit's, fat soluble

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