IgE-mediated cow’s milk allergy

In an IgE-mediated allergy, symptoms usually appear within minutes or up to two hours after eating anything that contains cow’s milk protein. This is because the immune system reacts to cow’s milk protein by producing IgE antibodies. These antibodies are produced by immune cells and activate the immune system to release chemicals such as histamines, which then trigger an immediate allergic reaction.

If it is IgE-mediated cow’s milk allergy, you may notice:

• Skin symptoms such as itchy rash, hives and swelling of the lips, tongue or face
• Gastrointestinal symptoms such as tummy pain, vomiting and diarrhoea
• Hay fever-like symptoms such as sneezing and an itchy, runny or blocked nose
• Breathing difficulties

In very severe cases, an IgE-mediated allergic reaction could lead to anaphylaxis — a potentially life-threatening allergic reaction that comes on quickly, affects the whole body, and requires medical help straight away. Fortunately, this type of allergic reaction is uncommon.

Non-IgE-mediated cow’s milk allergy

In non-IgE-mediated cow’s milk allergy, symptoms usually appear after two hours or up to a few days after eating anything containing cow’s milk protein.

Some symptoms of non-IgE-mediated allergy can be similar to those of IgE-mediated allergy. Others might be less obvious and could be mistaken for something other than a food allergy. The signs of non-IgE-mediated cow’s milk allergy could include:

• Colic-type symptoms
• Skin symptoms such as eczema and itching
• Reflux
• Gastrointestinal symptoms such as unusual stools, tummy pain and constipation

Mixed allergic reaction

Some babies with cow's milk allergy can have mixed allergic reactions, where they have symptoms of both IgE-mediated and non-IgE-mediated allergy. This means that the symptoms could come on quickly after eating or drinking anything with cow's milk protein and they could also appear after a few days.

Find out more about the symptoms of cow’s milk allergy.