Mustard-directed oral immunotherapy and structured oral exposure: lessons from four children

Background Mustard allergy is uncommon but can cause severe reactions, while mustard-specific oral immunotherapy (OIT) data are almost absent. Methods We retrospectively described four children managed with mustard-directed OIT or structured oral exposure at two French centers and updated a focused PubMed search through 17 October 2026. Pretreatment diagnostic certainty varied. Continued maintenance was defined pragmatically as ingestion according to the documented home regimen at latest follow-up and was not equated with desensitization. Results Ages at treatment initiation ranged from 4 to 12 years. Two younger children progressed to 3 g of prepared commercial mustard condiment daily without a documented treatment-requiring maintenance reaction, although baseline challenges did not establish unequivocal systemic thresholds. An 11-year-old boy with previous systemic reactions and mustard-specific IgE >100 kUA/L developed pruritus, paroxysmal cough, and conjunctivitis during escalation to 420 mg mustard ingredient in mayonnaise; symptoms resolved with desloratadine and inhaled salbutamol. He later discontinued because of recurrent dosing-related symptoms despite dose reduction. A 12-year-old boy progressed to 5 g mustard daily and subsequently once or twice weekly. Products, dose units, diagnostic certainty, and maintenance schedules were heterogeneous, and mustard-protein doses were not analytically quantified. Conclusion This series describes heterogeneous real-world pathways of mustard-directed OIT and structured oral exposure, including treatment-limiting intolerance, but does not establish an efficacy or desensitization rate. Future studies require prespecified diagnostic criteria, explicit product characterization and dose units, prospective safety and adherence capture, defined maintenance schedules, patient-centered outcomes, and standardized outcome challenges.