A rash is a change in skin which affects its color, appearance, or texture. A rash may be localized to one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, dry, cracked or blistered, swell and may be painful. The causes, and therefore treatments for, rashes vary widely. Diagnosis must take into account such things as the appearance of the rash, other symptoms, what the patient may have been exposed to, occupation, and occurrence in family members.
The presence of a rash may aid associated signs and symptoms are diagnostic of certain diseases. For example, the rash in measles is an erythematous, maculopapular rash that begins a few days after the fever starts; it classically starts at the head and spreads downwards.
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Causes |
Common causes of rashes include:
- anxiety
- allergies, for example to foods, dyes, medicines, insect stings, metals such as zinc or nickel; such rashes are often called hives.
- skin contact with an irritant
- bacterial or viral infection, e.g., by the viruses that cause chickenpox, smallpox, cold sores and measles
- fungal infection, such as ringworm
- reaction to vaccination
- skin diseases such as eczema or acne
- exposure to sun (sunburn) or heat
- irritation such as caused by abrasives impregnated in clothing rubbing the skin. The cloth itself may be abrasive enough for some people
Uncommon causes:
- autoimmune disorders such as psoriasis
- lead poisoning
- pregnancy
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