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Allergic contact dermatitis - Hair and Scalp

See also in: Overview,Cellulitis DDx,External and Internal Eye,Anogenital,Nail and Distal Digit,Oral Mucosal Lesion
Contributors: Priyanka Vedak MD, Susan Burgin MD
Other Resources UpToDate PubMed

Synopsis

This summary discusses adult patients. Allergic contact dermatitis in children is addressed separately.

Contact dermatitis presents as either allergic or irritant in etiology. While irritant contact dermatitis represents the direct toxic effect of an offending agent on the skin, allergic contact dermatitis (ACD) represents a delayed-type (type IV) hypersensitivity reaction that occurs when allergens activate antigen-specific T cells in a sensitized individual. Consequently, whereas irritant contact dermatitis can occur after one exposure to the offending agent, ACD typically requires repeat exposures before an allergic response is noted. ACD can occur 24-48 hours after exposure to the offending agent.

Contact dermatitis can demonstrate well-demarcated borders, suggestive of an "outside job" or external contact. The most common contact allergens are urishiol (poison ivy, oak, or sumac), nickel, fragrance, cobalt (a metal; see also cobalt toxicity), chromates (leather products), neomycin, thimerosal (ophthalmic preparations and vaccines), adhesives, and oxybenzone (sunscreens). The distribution and geometry of lesions are important clues to diagnosis. It can also present as a systemic contact reaction with widespread lesions when the offending agent is ingested or present in an implanted device. ACD can occur in reaction to topical agents, ingested agents, implanted biomedical devices, and airborne materials.

Codes

ICD10CM:
L23.9 – Allergic contact dermatitis, unspecified cause

SNOMEDCT:
40275004 – Contact dermatitis

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed:10/02/2017
Last Updated:10/05/2021
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Allergic contact dermatitis - Hair and Scalp
See also in: Overview,Cellulitis DDx,External and Internal Eye,Anogenital,Nail and Distal Digit,Oral Mucosal Lesion
A medical illustration showing key findings of Allergic contact dermatitis : Erythema, Scaly plaque, Vesicle, Pruritus
Clinical image of Allergic contact dermatitis - imageId=1446. Click to open in gallery.  caption: 'A close-up of round and oval, pink plaques with scant scale.'
A close-up of round and oval, pink plaques with scant scale.
Copyright © 2022 VisualDx®. All rights reserved.