Improvement of Chronic Spontaneous Urticaria After Glucagon-Like Peptide 1 Receptor Agonist Therapy: Report of Two Cases.

Chronic spontaneous urticaria (CSU) is a mast cell-driven disease that affects approximately 1% of the population. Second-generation non-sedating H-antihistamines (H1AH) are considered the first-line treatment; however, a substantial proportion of patients remain refractory and require alternative therapeutic approaches, including anti-IgE antibodies or other agents that inhibit mast cell activation and degranulation. Glucagon-like peptide 1 receptor agonists (GLP-1RAs) are widely used for the treatment of type 2 diabetes mellitus and obesity and are known to reduce cardiovascular risk as well as comorbidities such as kidney disease and depression. In addition, GLP-1RAs have been reported to improve several autoimmune and autoinflammatory disorders, including dermatoses such as psoriasis, hidradenitis suppurativa, and atopic dermatitis. Several mechanisms have been proposed to explain the immunomodulatory effects of GLP-1RAs, including their influence on cytokine networks and immune cells, particularly mast cells. We report two female patients, aged 44 and 45 years, with long-standing CSU inadequately controlled on high-dose H1AH, who were initially prescreened for participation in a clinical trial with barzolvolimab. Before trial enrollment, both initiated GLP-1RA therapy (semaglutide or tirzepatide) for metabolic indications. Remarkably, both patients achieved complete resolution of CSU within 3 weeks of GLP-1RA initiation, with remission persisting for over 6 months. These observations suggest a potential immunometabolic mechanism linking GLP-1 signaling and mast cell activation, highlighting a novel therapeutic avenue for antihistamine-resistant CSU.