Casein is a milk protein found in animal milk products. It is particularly high in cow milk products. Casein may cause symptoms if you are allergic or sensitive to casein-milk protein, but IgE antibodies are only present in case of allergy. Milk protein allergy can be confused with lactose intolerance because they have similar symptoms, and both occur when milk is consumed. With casein allergy, your immune system overreacts and produces IgE-protective antibodies. This can cause symptoms like itchy eyes, face or throat swelling, skin reactions, nasal congestion, runny nose, and cough.
The most common symptom of casein intolerance is stomach upset. Casein allergy can be life-threatening in severe cases, so it is important to distinguish whether you are allergic or suffer from casein or lactose intolerance.
What do the results mean?
A positive IgE casein test means that you are allergic to the milk protein casein. A negative IgE casein test rules out an allergy to milk but cannot rule out casein sensitivity or lactose intolerance.
What causes casein allergy?
Casein allergy is caused when the immune system mistakenly identifies a protein in cow's milk as harmful and triggers an allergic reaction.