Contact dermatitis

Last reviewed: 2 Nov 2022

Last updated: 14 May 2019

Irritant contact dermatitis is caused by direct toxicity without prior sensitization, and allergic contact dermatitis is a delayed hypersensitivity reaction.

Results in localized burning, stinging, itching, blistering, redness, and swelling at the area of contact with the allergen or irritant.

Patch testing may aid identification of the causative agent. Skin biopsy may also be helpful, but may not be able to distinguish between other causes of dermatitis.

Treatment involves removal of the causative agent, future avoidance of the causative agent, topical corticosteroids, and/or a short course of oral corticosteroids.

Rarely, contact dermatitis can become generalized, leading to areas of dermatitis in locations distant from the site of contact with the causative agent.

Other allergic conditions may be triggered by exposure to an allergen, such as allergic rhinitis, asthma, and anaphylaxis.

Definition

Contact dermatitis is an allergic or irritant skin reaction caused by an external agent.

History and exam

Key diagnostic factors

occupational history of exposure
history of atopic dermatitis
previous episodes of similar dermatitis
acute onset
affecting hands and face
affecting sun-exposed skin
sparing of non-exposed areas of skin
pruritus
burning
erythema
vesicles and bullae
urticaria
lichenoid lesions
corrosion or ulceration
pustules and acneiform lesions

More key diagnostic factors

Other diagnostic factors

social history of exposure
persistence of symptoms
scaling
lichenification
crusting
erythema multiforme
cellulitic lesions
leukoderma
hypopigmentation
hyperpigmentation
purpura
miliaria
alopecia
granulomatous lesions

Other diagnostic factors

Risk factors

occupation with frequent exposure to water or caustic material
atopic dermatitis

More risk factors

Diagnostic investigations

1st investigations to order

patch testing
repeated open application test (ROAT) or provocative use test (PUT)

More 1st investigations to order

Investigations to consider

skin biopsy

More investigations to consider

Emerging tests

reflectance confocal microscopy (RCM)

Treatment algorithm

ACUTE

irritant contact dermatitis

allergic contact dermatitis (ACD)

ONGOING