The use of biological targeted therapy for allergic diseases has significantly increased the effectiveness of the treatment of patients with atopic dermatitis, bronchial asthma, and combined allergopathology. Dupilumab, a monoclonal antibody drug that blocks signaling from IL-4 and IL-13, is one of the options for biological therapy aimed at modifying the Th2 immune response. The article discusses current ideas about the pathogenesis of allergic Th2-dependent inflammation, about the key mechanisms of the formation of atopic dermatosis and its role in inducing the progressive course of atopy. A clinical example of successful treatment of an 8-year-old child with severe atopic dermatitis, moderate partially controlled bronchial asthma, allergic rhinitis, and multisensitization to food and pollen allergens is given. The use of biological targeted therapy with dupilumab made it possible to achieve sustainable remission in the course of atopic dermatitis and bronchial asthma. The SCORAD index, which was 66.8 points before dupilumab treatment, decreased to 8.9 points. Immunobiological therapy with an IL-4Rα inhibitor, dupilumab, is indicated for patients with moderate to severe allergic diseases when it is not possible to achieve adequate control with standard treatment methods. The presented clinical case of the use of the drug contributes to the study of the clinical efficacy and safety of dupilumab during its long-term use.