Contact Dermatitis & Patch Testing: 2026 Updates for Allergists (Recording)

This webinar was recorded on September 30, 2026 

Allergic contact dermatitis (ACD) has long been dermatology’s domain—but as Dr. Luz Fonacier, MD, Professor of Medicine at NYU Long Island School of Medicine and Past President of the ACAAI, emphasizes, this is fundamentally an allergic disease that belongs in the allergist’s wheelhouse. Here are the critical takeaways allergists need to know.

1. Location, Location, Location

Dr. Fonacier’s diagnostic mantra: dermatitis distribution tells the story. The five hallmark zones—hands, face, eyelids, lips, and scattered/generalized patterns—each point toward distinct allergen categories, from fragrance-laden cosmetics to rubber accelerators in gloves.

2. Patch Testing Accelerates Resolution—By 143 Days

A retrospective study of 270 ACD patients found that patch-tested individuals achieved symptom relief 143 days sooner than those diagnosed by history alone. Testing proved most cost-effective within 2 months to 1 year of disease onset.

3. The MI Epidemic Is Real

Methylisothiazolinone (MI) now ranks as the second most common positive patch test allergen, with a 13.8% positivity rate. Testing MCI/MI alone misses roughly 40% of true MI allergy—a critical screening gap.

4. Eyelid Dermatitis Is Allergic Until Proven Otherwise

When eyelid involvement extends beyond the orbit, 55–72% of cases are allergic in origin—driven primarily by fragrances, gold, nickel, and balsam of Peru.

5. Lanoline’s Paradox

Sensitization to lanoline is paradoxically low in normal skin, moderate in atopic dermatitis, and highest in stasis dermatitis—a nuance that should inform testing strategy in your most vulnerable patients.

6. Topical Corticosteroids Can Betray You

Between 0.5–5% of dermatitis patients harbor corticosteroid allergy, with 85% reacting to multiple steroid molecules. Watch for the telltale “ring reaction”—and remember, 30% of positive reactions are missed without a day 6–7 late reading.

7. Systemic Contact Dermatitis Deserves a Dietary Workup

Nickel and balsam of Peru are the leading culprits in systemic contact dermatitis. For refractory, widespread eczema, a 6-week low-nickel or low-balsam elimination diet may be diagnostic and therapeutic—though robust guidelines remain limited.

8. New Allergen Frontiers: Tattoos, Wearables, and Diabetic Devices

Para-phenylenediamine sensitization now stems increasingly from temporary tattoos and body paint, not just hair dye—with lifelong implications for future hair coloring. Meanwhile, isobornyl acrylate in diabetic devices represents “one of the most significant recent consumer allergen problems,” per Dr. Fonacier, often with no viable substitute.

9. “Nonallergens” Worth Knowing

Both gold and thimerosal generate high patch-test positivity but low clinical relevance (10–15% and essentially historical, respectively). Neither contact sensitivity should delay vaccination.

Dr. Fonacier’s practice parameters—currently in development with an estimated two-year timeline—aim to formalize what her data already shows: patch testing is the gold standard, empiric avoidance has real limitations, and allergists are uniquely positioned to close the diagnostic gap. As she notes, “the greatest abuse of patch testing is the failure to use the test.” For clinicians managing refractory dermatitis, hand eczema, or atypical eyelid and facial presentations, the message is clear—test early, test specifically, and don’t mistake “natural” for “hypoallergenic.”

Target Audience 

This activity is designed for allergists, immunologists, advanced practice providers, fellows, and other healthcare professionals involved in the care of patients with asthma and allergic diseases.     

Speaker

Luz Fonacier, MD 

Dr. Fonacier is a Professor of Medicine at NYU Long Island School of Medicine and is the Head of Allergy and Training Program Director in Allergy and Immunology at NYU Winthrop Hospital.  the past president of the American College of Allergy, Asthma and Immunology (ACAAI) and the past chair of the American Board of Allergy and Immunology. Dr. Fonacier has numerous publications in textbooks and journals. Because of her training in dermatology, allergy, and immunology, her special interest is the dermatologic manifestations of allergic diseases 

This Advances webinar is in partnership with the American College of Allergy, Asthma & Immunology. ACAAI offers CMEs for physicians for this webinar. If you are an ACAAI member, you can obtain CME through the member portal for this Advances webinar. 

Sponsored by the American College of Allergy, Asthma and Immunology