What is the relationship between eczema and egg allergy?

There is a high rate of co-occurrence between egg allergy and eczema (atopic dermatitis). A 2023 meta-analysis of observational studies found that 54.9% of people with a challenge-proven food allergy also had eczema, which represented 4 to 5 times greater odds compared to those without a food allergy.^[1] Interestingly, some individuals with egg allergy and eczema may notice an improvement in eczema following egg avoidance.^[2]

The dual allergen exposure hypothesis proposes that sensitization to a food allergen (e.g., egg protein) may occur when an infant's first exposure occurs via absorption through an impaired skin barrier, such as in eczema, rather than through oral consumption. While initial interactions with the immune system through the gastrointestinal tract are suggested to promote oral tolerance, exposure through the skin may instead promote sensitization — a prerequisite for food allergy. This is merely a theory and a causal relationship has not been confirmed. However, research has found that children may be sensitized to egg proteins before the oral introduction of egg; eczema usually precedes egg allergy; the risk of food allergy increases with increasing eczema severity; early oral introduction may prevent allergy; and genetic mutations leading to impaired skin barrier function are associated with an increased risk of food allergies.^[3][1][4][5]