Clinical Characteristics and Patch Test Results in 57 Patients with Contact Dermatitis in Southern Taiwan

<b>Background/Objectives</b>: Patch testing is a valuable clinical tool for identifying the causes of allergic contact dermatitis (ACD). This study aimed to identify common allergens in southern Taiwan. <b>Methods</b>: A retrospective review of patch test data from April 2019 to May 2023 was conducted at a tertiary medical center. The European Baseline Series of allergens was utilized to evaluate and identify the causes of dermatitis. The prevalence rates of contact sensitization to each allergen were calculated. <b>Results</b>: A total of 57 patients (mean age 41.8 years) with contact dermatitis who underwent patch testing were included. The most common allergens were cobalt chloride (24.6%), followed by fragrance mix I (19.3%), Peru balsam (17.5%), nickel (II) sulfate hexahydrate (15.8%), benzisothiazolinone (15.8%), 4-Phenylenediamine (PPD) base (10.5%), and methyldibromo glutaronitrile (10.5%). Patients with positive patch test results frequently had a history of allergic rhinitis (26.3%), atopic dermatitis (24.6%), urticaria (21.1%), and elevated immunoglobulin E (IgE) levels (28.1%). The hairdressing profession was associated with a higher risk of hand eczematous dermatitis. <b>Conclusions</b>: Positive patch test results were observed in 86% of patients diagnosed with contact dermatitis. This study found that cobalt, rather than nickel, was the most prevalent allergen in patients with contact dermatitis. Elevated IgE levels were observed in ACD patients, with the hands being the most frequently affected area. Occupations as accountants, secretaries, and in the hairdressing and cosmetics industries were strongly associated with hand eczematous dermatitis. The early identification of allergens and appropriate treatment strategies significantly reduced recurrence rates and improved outcomes. For individuals with specific allergies, ongoing avoidance of identified allergens is crucial to managing and preventing allergic reactions. Further research is needed to elucidate the mechanisms and responses to novel therapies, including biologic agent- and nanotechnology-based treatments.