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Dermatitis - contact - Background information
What is it?
- Contact dermatitis is an inflammatory skin reaction (dermatitis) that occurs in response to an external agent acting as either an irritant or an allergen:
- Allergic contact dermatitis is a type IV delayed hypersensitivity reaction that occurs after sensitization and subsequent re-exposure to an allergen.
- Irritant contact dermatitis is an inflammatory response that occurs after damage to the skin, usually by chemicals. It may occur in any individual exposed to an irritant for a sufficient duration and in sufficient concentration:
- Acute irritant contact dermatitis results from a single overwhelming exposure or a few brief exposures to strong irritants.
- Cumulative or chronic irritant contact dermatitis occurs because of repeated exposures to weaker irritants.
- In practice, allergic and irritant contact dermatitis often co-exist.
- Physical conditions, such as heat, cold, repeated frictional exposure, or low humidity, can increase the likelihood and severity of contact dermatitis, particularly irritant contact dermatitis.
[Bourke et al, 2001; Beltrani et al, 2006; Mark and Slavin, 2006]
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