Milk and egg allergies are the most prevalent food allergies affecting infants and young children. The prevalence of milk allergy is 2-3% in young children but may be higher if non-IgE-mediated allergy to milk is included. Over 90% of those with a milk allergy will achieve tolerance by adult life. Adults reporting reactions to milk are most likely to be lactose intolerant (link to non-immune mediated section) but two thirds of adults with a milk allergy develop it in adult life, so it should not be ruled out, especially if respiratory or cardiovascular symptoms are reported. The majority of infants and children with mild/moderate milk allergy can be managed in primary care on an extensively hydrolysed formula milk. Amino acid formula milks should be considered if the child has had anaphylaxis, faltering growth or no improvement on an extensively hydrolysed formula. The formula chosen should be continued until the age of two years, unless a nutritional review demonstrates that the diet is sufficient to meet the nutritional needs of the child at an earlier age. Sheep and goats’ milk are not suitable for milk-allergic individuals. Plant-based milks made from soya, rice, hemp, potato, nut, coconut, pea or oat, are suitable for older children and adults, but might not provide sufficient nutrition for pre-school children. Also, inorganic arsenic is a natural component of rice milks, so they should not be consumed by children younger than 4.5 years. The supervised use of a milk ladder to gradually introduce baked and raw milk into the diet should be considered for all patients, especially those with mild to moderate milk allergy. There are many guidelines on milk allergy with advice for children being managed in primary or secondary care.
Egg allergy affects up to 2% of children, and like milk allergy, often resolves in childhood. Those with a persisting egg allergy might tolerate cooked or baked egg but not raw egg. Rarely, a new-onset egg allergy can develop in adults, often to egg yolk and due to cross-reactivity between an allergen in egg yolk and an allergen in birds’ feathers. Since egg allergy commonly resolves over time, the introduction of baked egg should be encouraged, through the use of egg ladders.
Prolonged total exclusion of egg could influence the persistence of the condition and make it more difficult from a dietary perspective. Although eggs are not the sole source of nutrition in young children, their exclusion might appear to have fewer nutritional consequences, but eggs are a constituent ingredient in many foods, which may severe limit the diet, especially if the ability to bake egg free alternatives is not an option.
Allergy to either milk or egg can be diagnosed through history and skin prick or specific IgE tests. In older children or adults, CRD tests can reveal whether there is sensitisation to the major heat-resistant allergens in milk (Bos d 8) or egg (Gal d 1), which might enable decisions to be made about the likely persistence of the allergy and the risk/benefit of an oral food challenge.