ALLERGIC CONTACT DERMATITIS

By Gary M. White, MD

Allergic contact dermatitis of the hand from paragons in a hand cleanser Allergic contact dermatitis to the paraben in a hand cleanser.


Allergic contact dermatitis (ACD) is the cell-mediated immune reaction to an allergen that has come in contact with the skin.

Clinical

An eczematous, red, scaly, itchy rash develops at the site of skin contact with the allergen. Vesicles and bulla may form. Oozing of fluid is common in severe cases. Occasionally, men may transfer the allergen to the penis, causing significant swelling.

Diagnosis

The history is critical. Exposure to the allergen with direct contact to the skin days or even a week before onset of the rash is typical. Patch testing (PT) is confirmatory.

Treatment

Of course, avoidance of the allergen is key. A strong topical steroid, e.g., clobetasol, is in order. For diffuse cases, a course of oral corticosteroids, e.g., prednisone 1 mg/kg/day initially and tapered over 10-14 days, may be needed. Tapering too soon results in a flare.

For chronic cases, where the cause is unknown, patch testing is invaluable.

The "Pre-Emptive Avoidance Strategy" (P.E.A.S.)

If patch testing is difficult or impractical, one option is preemptive avoidance in which the patient avoids the top 10 allergens for their demographic. For example, for children, the top ten allergens are neomycin, balsam of Peru, fragrance mix, lanolin, cocamidopropyl betaine, formaldehyde, corticosteroids, methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), propylene glycol, and benzalkonium chloride. The authors of this article [Expert Review of Clinical Immunology 2016;12] estimate that one third of children suffering from ACD could potentially benefit from a "pre-emptive avoidance strategy" (P.E.A.S.).

Additional Pictures

This young girl picked flowers the day before.
Allergic contact dermatitis to plants Allergic contact dermatitis to plants

ACD to a topical product causing acute facial swelling and edema.
Allergic contact dermatitis to a facial lotion Allergic contact dermatitis to a facial lotion

Allergic contact dermatitis to nickel.
Allergic contact dermatitis to nickel in glasses Allergic contact dermatitis to nickel in glasses

Allergic contact dermatitis to lipstick.
Allergic contact dermatitis to lipstick

Allergic contact dermatitis to bleached elastic.
Allergic contact dermatitis to the elastic in underwear

Allergic contact dermatitis to hair dye (paraphenylenediamine).
Allergic contact dermatitis to hair dye

Note the angulated nature of the border of the bulla.
Allergic contact dermatitis on the arm

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