Essential History Questions for Dermatology Patch Testing Clinic Consult
A structured history for patch testing must identify the dermatitis pattern, potential allergen exposures, and factors that could cause false-negative results.
Dermatitis Characteristics and Distribution
Where did the dermatitis first appear, and how has it spread? This identifies the primary site and helps distinguish localized allergic contact dermatitis from generalized patterns 1.
Is the dermatitis chronic or persistent (lasting >6 weeks)? Patch testing is indicated for any chronic or persistent dermatitis, as clinical features alone cannot reliably distinguish allergic from irritant or endogenous causes 1.
Does the distribution suggest contact with specific items? Ask specifically about marked facial/eyelid involvement, increased severity at neck flexures, vesicular lesions on dorsal hands and fingertips, or unusual patterns like sides of feet 1, 2.
For atopic dermatitis patients: Has previously well-controlled dermatitis become difficult or impossible to control with the same topical treatments? This signals possible superimposed allergic contact dermatitis 1, 2.
Occupational and Environmental Exposures
What is your occupation, and what specific chemicals, materials, or products do you handle at work? Request Material Safety Data Sheets for workplace chemicals 1, 3.
Do symptoms improve on weekends and holidays, then recur upon return to work? This temporal pattern strongly suggests occupational contact dermatitis 1.
What hobbies or recreational activities do you engage in? These may involve allergen exposures not present in daily work 1.
Do symptoms worsen after sunlight exposure? This suggests possible photoallergic contact dermatitis 1.
Product and Allergen Exposures
What specific topical products do you use on affected areas? Include moisturizers, cosmetics, topical medications, cleansers, and their frequency of use 1.
Have you used topical antibiotics (neomycin, bacitracin), fragrances, preservatives, or adhesive bandages on affected skin? These are common allergens in atopic dermatitis patients 1.
What products cause immediate worsening of symptoms? Document specific brand names and bring products to the appointment for assessment 1.
Irritant Exposures
How frequently do you wash your hands, and what do you wash them with? Include water exposure frequency, use of soaps versus synthetic detergents, and water temperature 1.
Do you have contact with wet agents (water, detergents) or dry, desiccating products? Both are primary skin irritants that must be distinguished from allergens 1.
Do you work with known irritants like bleach, dish detergent, or disinfectant wipes? These cause irritant contact dermatitis but may coexist with allergic contact dermatitis 1, 4.
Factors Affecting Patch Test Validity
Have you had natural sun exposure or used tanning beds in the past 6 weeks? UV exposure must be avoided for 6 weeks before testing to prevent false-negatives 1, 3.
Are you currently taking or have you recently stopped systemic medications? Defer testing for 3 months after systemic agents and 6 months after biologics 1, 3.
Are you currently using topical corticosteroids on your back? Potent topical steroids must be avoided on the back for 2 days before testing 4.
Are you taking oral corticosteroids or immunosuppressants? If unavoidable, keep prednisolone ≤10 mg daily, though results may be suboptimal 1, 4.
Are you pregnant or breastfeeding? No evidence of harm with breastfeeding; pregnancy requires informed consent as safety data are unavailable 1.
Medical History
Do you have atopic dermatitis, and if so, when did it begin? Adult- or adolescent-onset atopic dermatitis warrants patch testing, as does therapy-resistant hand eczema in working-age patients 1, 2.
Is there a family history of atopy? Absence of family history in a patient with "atopic dermatitis" raises suspicion for allergic contact dermatitis 1.
Have you had previous patch testing, and if so, what were the results? Only 17% of patients remember the allergen name after 10 years, despite 79% remembering they had a positive test 3.
Have you ever had severe allergic reactions to any substances? Known history of severe reactions to suspected allergens is a contraindication to patch testing 5.
Common Pitfalls to Avoid
Do not proceed with patch testing if the patient has generalized active dermatitis or extensive eczema covering potential test sites, as this is a contraindication and may cause excited skin syndrome 5, 6.
Do not assume antihistamines need to be stopped unless specifically testing for urticaria or contact urticarial reactions 1.
Do not overlook glove-related exposures: Ask specifically about glove type (latex, nitrile, vinyl), duration of wear, and whether moisturizer is applied before gloving 1, 4.