Rash
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| ICD-10 | R21 |
| ICD-O: | {{{ICDO}}} |
| ICD-9 | 782.1 |
| OMIM | {{{OMIM}}} |
| MedlinePlus | {{{MedlinePlus}}} |
| eMedicine | {{{eMedicineSubj}}}/{{{eMedicineTopic}}} |
| DiseasesDB | {{{DiseasesDB}}} |
A rash is a change in the skin which affects its appearance or texture. A rash may be localised to one part of the body, or affect all the skin. Rashes may cause the skin to change colour, 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 diagnosis of the patient's condition. Not only the appearance and sensation of the rash but also the distribution (which parts of the body are affected and where it arose and spread to) and evolution of the rash may be important as certain patterns of rashes and their 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.
Causes
Common causes of rashes include:
- allergies, for example to foods, dyes, medicines, insect stings; such rashes are often called hives
- skin contact with an irritant
- infection or reaction to a vaccine
- skin diseases such as eczema or acne
- autoimmune disorders such as psoriasis
- cancer or other disease
- pregnancy
- exposure to sun or heat
- lead poisoning