Patch Test Reactions Associated With Topical Medications: A Retrospective Analysis of the North American Contact Dermatitis Group Data (2001-2018)

Background/Objectives Topical medications may lead to allergic contact dermatitis. This study characterized positive patch test reactions associated with medications in patients evaluated by the North American Contact Dermatitis Group (NACDG). Methods This study is a retrospective analysis of the NACDG data (2001-2018). Patients with at least 1 positive patch test reaction associated with a medication source were included. Allergens, reaction characteristics, clinical relevance, and source details were tabulated. Results Of 43,722 patients, 6374 (14.6%) had positive allergic patch test reactions associated with 1 or more topical medication sources. Patients with versus without allergic reactions to medications were more likely to be older than 40 years (P < 0.0001) and/or have primary sites of dermatitis on the legs, anal/genital region, or trunk (P < 0.0001). There were 8787 reactions to NACDG allergens; the most common were neomycin (29.4%), bacitracin (29.1%), propylene glycol 100% (10.6%), tixocortol-17-pivalate (10.0%), lidocaine (7.9%), budesonide (4.9%), and dibucaine (4.4%). Propylene glycol 100% was the most common inactive ingredient (10.6%). Current relevance was present in 61.0%. A total of 6.5% of the individuals with medication allergy would have had 1 or more positive patch test reactions missed if only tested to the NACDG screening series. Conclusions Positive patch test reactions associated with topical medications were common (14.6%), and most were clinically relevant. Patients with topical medication allergy were twice as likely to have anal/genital involvement. Active ingredients, especially neomycin, bacitracin, and tixocortol-17-pivalate, were frequent culprits.

Automated summary

This study retrospectively analyzed data from the North American Contact Dermatitis Group (NACDG) and found that positive patch test reactions associated with topical medications were common and clinically relevant. Patients with medication allergy, especially those over 40 years old and with primary sites of dermatitis on the legs, anal/genital region, or trunk, were more likely to have allergic reactions to medications. Active ingredients like neomycin, bacitracin, and tixocortol-17-pivalate were frequent culprits.