More than just methylisothiazolinone: Retrospective analysis of patients with isothiazolinone allergy in North America, 2017-2020

Margo J. Reeder, Department of Dermatology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. Electronic address: mreeder@dermatology.wisc.edu.
Donglin Zhang, Department of Dermatology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
Srikanth R. Aravamuthan, Department of Dermatology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
Erin M. Warshaw, Department of Dermatology, Park Nicollet Health Services, Minneapolis, Minnesota; Department of Dermatology, Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota; Department of Dermatology, University of Minnesota, Minneapolis, Minnesota.
Joel G. DeKoven, Division of Dermatology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada.
Jonathan I. Silverberg, Department of Dermatology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia.
Brandon L. Adler, Department of Dermatology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Amber R. Atwater, Department of Dermatology, Duke University Medical Center, Durham, North Carolina.
James S. Taylor, Department of Dermatology, Cleveland Clinic, Cleveland, Ohio.
Marie-Claude Houle, Division of Dermatology, CHU de Quebec, Laval University, Quebec City, Canada.
Donald V. Belsito, Department of Dermatology, Columbia University Irving Medical School, New York, New York.
Jiade Yu, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
Nina Botto, Department of Dermatology, University of California, San Francisco, San Francisco, California.
Christen M. Mowad, Department of Dermatology, Geisinger Medical Center, Danville, Pennsylvania.
Cory A. Dunnick, Department of Dermatology, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Dermatology, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, Colorado.
Vincent A. DeLeo, Department of Dermatology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Melanie D. Pratt, Division of Dermatology, University of Ottawa, Ottawa, Canada.

Document Type

Journal Article

Publication Date

10-23-2023

Journal

Journal of the American Academy of Dermatology

DOI

10.1016/j.jaad.2023.10.032

Keywords

allergic contact dermatitis; methylisothiazolinone; patch testing

Abstract

BACKGROUND: Isothiazolinones are a common cause of allergic contact dermatitis. OBJECTIVE: To examine the prevalence of positive patch test reactions to isothiazolinones from 2017-2020 and characterize isothiazolinone-allergic (Is+) patients compared with isothiazolinone nonallergic (Is-) patients. METHODS: Retrospective cross-sectional analysis of 9028 patients patch tested to methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) 0.02% aqueous, MI 0.2% aqueous, benzisothiazolinone (BIT) 0.1% petrolatum, and/or octylisothiazolinone (OIT) 0.025% petrolatum. Prevalence, reaction strength, concurrent reactions, clinical relevance, and source of allergens were tabulated. RESULTS: In total, 21.9% (1976/9028) of patients had a positive reaction to 1 or more isothiazolinones. Positivity to MI was 14.4% (1296/9012), MCI/MI was 10.0% (903/9017), BIT was 8.6% (777/9018), and OIT was 05% (49/9028). Compared with Is-, Is+ patients were more likely to have occupational skin disease (16.5% vs 10.3%, P <.001), primary hand dermatitis (30.2% vs 19.7%, P <.001), and be >40 years (73.1% vs 61.9%, P <.001). Positive patch test reactions to >1 isothiazolinone occurred in 44.1% (871/1976) of Is+ patients. Testing solely to MCI/MI would miss 47.3% (611/1292) of MI and 60.1% (466/776) of BIT allergic reactions. LIMITATIONS: Retrospective cross-sectional study design and lack of follow-up data. CONCLUSION: Sensitization to isothiazolinones is high and concurrent sensitization to multiple isothiazolinone allergens is common.

Department

Dermatology

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