Could egg yolk be the first approach in oral challenges for egg allergy tolerance?

Background. Hen's egg allergy is one of the most common pediatric food allergies, requiring accurate diagnosis and management strategies. Oral food challenges (OFCs) are critical in evaluating food allergies; however, limited research has focused on the outcomes of challenges involving egg yolks. This retrospective study aims to assess the outcomes and characteristics of pediatric patients who underwent oral challenges with boiled egg yolk. Methods. We evaluated patients diagnosed with egg allergy who underwent an OFC with egg yolk between 2019 and 2022. Results. The study included 123 patients with a median age of 12 months. The first presentation of symptoms occurred at a mean age of 6 months. Initial symptoms included eczema flare-ups (70%), urticaria (13.8%), and anaphylaxis (8.9%). The median age of the first egg yolk OFC was 12 months. For the first egg white OFC to assess the tolerance, the median age was 16 months.  Of the 123 egg yolk OFCs, 115 (93.4%) patients were tolerant and consumed egg yolk at home. In the egg yolk-tolerant group, the mean duration of egg white tolerance was 4 months post-OFC; for non-tolerant patients, this extended to 11 months. The egg yolk non-tolerant group had higher egg white-specific IgE levels than the tolerant group (28 kU/L [IQR: 2.4-85.9] vs. 4.2 kU/L [IQR: 0.9-8.8], p<0.01). Conclusions. Though mild symptoms may occur, most children with egg allergies can safely consume boiled egg yolk. Consuming hen's egg yolk after a negative OFC could expand dietary options and improve quality of life.