Egg allergy

Egg allergy is an adverse immune response, primarily IgE-mediated, to proteins found in eggs that can lead to a range of allergic reactions from mild skin rashes to severe anaphylaxis.

The allergic reaction is primarily mediated by IgE antibodies, leading to the release of inflammatory mediators and systemic inflammation. Sensitization can occur to egg white proteins (such as ovomucoid, ovalbumin, ovotransferrin, and lysozyme) or egg yolk proteins (such as albumin). In rare cases, cross-reactivity to chicken meat may occur.

Egg allergy primarily affects infants and young children but can also occur in adults. It is one of the most prevalent food allergies in childhood, with an estimated prevalence of 0.5-2.5% in young children and and 0.1% in adults. New-onset egg allergy in adults is rare, tends to be more severe, and often persists.

Risk factors for egg allergy include personal history of asthma, allergic rhinitis, or atopic dermatitis, family history of food allergies, late introduction of eggs, and antibiotic use in the first week of life.

Egg allergy presents most commonly in infancy, usually as an immediate allergic reaction, such as urticaria, angioedema, and/or vomiting, shortly after ingestion of eggs. Symptoms typically appear within minutes to one hour but may be delayed up to two hours. The skin and mucosa are most frequently affected, while severe reactions involving respiratory and cardiovascular symptoms, presenting with cough, wheezing, dyspnea, or pallor, are uncommon.

The prognosis of egg allergy is generally favorable, with most children developing tolerance by late childhood. Baseline egg-specific Iimmunoglobulin E levels and initial reaction characteristics are strongly associated with resolution, with individuals having egg IgE > 50 kU/L being unlikely to develop egg tolerance.