PURPOSE: The status of dupilumab self-injection at home is not well understood. We therefore aimed to identify the barriers to adherence to dupilumab self-injection. PATIENTS AND METHODS: This non-interventional open-label study was conducted between March 2021 and July 2021. Patients with atopic dermatitis, bronchial asthma, and chronic rhinosinusitis with nasal polyps receiving dupilumab, from 15 sites, were requested to complete a self-administered questionnaire regarding the frequency and effectiveness of dosing as well as their use and satisfaction with dupilumab. Barriers to adherence were assessed using the Adherence Starts with Knowledge-12. RESULTS: We included 331 patients who used dupilumab for atopic dermatitis (n = 164), chronic rhinosinusitis with nasal polyps (n = 102), and bronchial asthma (n = 65). The median efficacy of dupilumab scored 9.3 on the visual analog scale. Overall, 85.5% of the patients self-injected dupilumab, and 70.7% perfectly complied with the established injection dates. The pre-filled pen was significantly superior to the conventional syringe in terms of usability, operability, ease of pushing the plunger, and patient satisfaction. However, the pre-filled pen caused more pain during self-injection than did the syringe. Multivariate logistic regression analysis showed that adherence decreased with longer dupilumab treatment duration (p = 0.017) and was not associated with age, sex, underlying disease, or device type. There was a difference in responses related to "inconvenience/forgetfulness" between the good and poor adherence groups. CONCLUSION: The pre-filled dupilumab pen was superior to the syringe in terms of usability, operability, ease of pushing the plunger, and satisfaction. Repetitive instructions are recommended for preventing poor adherence to dupilumab self-injection.