Patch Testing Guidelines for Dermatology

Patient History and Characteristics

The British Journal of Dermatology recommends identifying the dermatitis pattern, potential allergen exposures, and factors that could cause false-negative results to determine the primary site and distinguish localized allergic contact dermatitis from generalized patterns 1, 2.
Patch testing is indicated for any chronic or persistent dermatitis, as clinical features alone cannot reliably distinguish allergic from irritant or endogenous causes, according to the British Journal of Dermatology 1, 2, 3.
The distribution of dermatitis can suggest contact with specific items, such as marked facial/eyelid involvement, increased severity at neck flexures, vesicular lesions on dorsal hands and fingertips, or unusual patterns like sides of feet, as noted in the Journal of the American Academy of Dermatology 4.

The British Journal of Dermatology suggests asking about occupation, specific chemicals, materials, or products handled at work, and requesting Material Safety Data Sheets for workplace chemicals 1, 5.
Symptoms that improve on weekends and holidays, then recur upon return to work, strongly suggest occupational contact dermatitis, according to the British Journal of Dermatology 1, 2.
Hobbies or recreational activities may involve allergen exposures not present in daily work, as noted in the British Journal of Dermatology 1.

The British Journal of Dermatology recommends asking about specific topical products used on affected areas, including moisturizers, cosmetics, topical medications, cleansers, and their frequency of use 1, 2.
Topical antibiotics, fragrances, preservatives, or adhesive bandages on affected skin are common allergens in atopic dermatitis patients, according to the Journal of the American Academy of Dermatology 4, 6.

The British Journal of Dermatology suggests asking about hand-washing frequency, soap or synthetic detergent use, and water temperature to identify potential irritant exposures 1, 2, 6.
Contact with wet agents or dry, desiccating products can cause irritant contact dermatitis, as noted in the British Journal of Dermatology 1, 2.
Working with known irritants like bleach, dish detergent, or disinfectant wipes can cause irritant contact dermatitis, according to the Journal of the American Academy of Dermatology 6.

The British Journal of Dermatology recommends avoiding natural sun exposure or tanning beds for 6 weeks before testing to prevent false-negatives 3, 2, 8.
Systemic medications should be avoided for 3 months, and biologics for 6 months, before patch testing, as noted in the British Journal of Dermatology 3, 2, 8.
Potent topical steroids should be avoided on the back for 2 days before testing, according to Praxis Medical Insights 7.

The Journal of the American Academy of Dermatology recommends patch testing for adult- or adolescent-onset atopic dermatitis, as well as therapy-resistant hand eczema in working-age patients 4.
A family history of atopy can help distinguish between atopic dermatitis and allergic contact dermatitis, as noted in the Journal of the American Academy of Dermatology 4.

The British Journal of Dermatology recommends not assuming antihistamines need to be stopped unless specifically testing for urticaria or contact urticarial reactions 1, 3.
Glove-related exposures, including type, duration of wear, and moisturizer use, should be considered, according to the Journal of the American Academy of Dermatology 6 and Praxis Medical Insights 7.