Introduction: Due to their ubiquitous use, isothiazolinones caused allergic contact dermatitis epidemics and their use was restricted by legal regulations. Objectives: We aimed to evaluate demographic data, clinical findings, and patch test features of patients with methylisothiazolinone (MI) and/or methylchloroisothiazolinone(MCI) sensitivity in our study. Methods: This study is a bidirectional and cross-sectional study, between July 2020 and September 2021. A total of 616 patients, including prospective and retrospective populations, demographic data, clinical findings, and patch test results were reviewed. Patients’ demographics, patch test results, allergen sources, presence of occupational contact, and the characteristics of dermatitis attacks were recorded. Results: A total of 50 patients with MI and MCI/MI sensitivity, 36 male (72%) and 14 female (28%), were included in our study. The overall prevalence of MI and MCI/MI between 2014 and 2021 was 8.4% (52/616) with two peak levels in 2015(21%) and 2021 (20%). A statistically significant relationship was found between shampoo use and facial involvement (p = 0.031), shower gel use and arm involvement (p = 0.027), wet wipe use and hand involvement (p = 0.049), detergent use and the pulps (p = 0.026) and the lateral aspects of fingers involvement (p = 0.048), water-based dye use and periungual involvement (p = 0.047). Conclusion: Although legal regulations related to MI and MCI/MI cause a decrease in the frequency of their sensitivities were still common causes of allergic contact dermatitis.