Cow's Milk Allergy
What is Cow’s Milk Allergy
Tags: cows milk allergy
Cow’s milk allergy (CMA) is one of the most common food allergies in infancy and early childhood. It is a hypersensitivity reaction to one or more bovine proteins found in cow milk and dairy products.
When a baby is allergic to cow’s milk, their immune system, which normally fights infections, overreacts to one or more bovine proteins in milk. As a result, every time the baby drinks milk or eats dairy products, the body thinks these proteins are harmful invaders this causes them to have a reaction.
CMA is sometimes confused with lactose intolerance. Both can cause problems after drinking milk or eating dairy products, but they are very different and unrelated.
CMA is a reaction to the PROTEIN in milk, while lactose intolerance is a reaction to the SUGAR (lactose) in milk. Therefore, lactose-free milk would not be helpful for a baby with suspected CMA. Of note, lactose intolerance is typically not found in babies.
Are there different types of cow milk allergy?
Yes. Cow milk allergy can be IgE mediated, non-IgE mediated or a mix of both.
IgE allergies are the classic allergies we think of when babies get hives/rashes and experience difficulty breathing after eating something. This allergy can be tested for with skin prick testing (and blood tests). These allergies are the ones that might need an epinephrine pen, steroid medicines, or Benadryl to manage. Reactions occur within minutes (or up to 2 hours) after drinking cow’s milk.
Non-IgE mediated cow milk allergy, on the other hand, is not driven by IgE but is considered a delayed hypersensitivity reaction. There is no risk of associated breathing problems or anaphylaxis with this type of allergy; however, many babies experience vomiting and/or blood/mucus in the stool. It is called a delayed hypersensitivity reaction because the symptoms don’t occur immediately but can take up to 48 hours (or even up to a week). The remainder of the talk will be about the non-IgE mediated cow milk allergy (also shortened to CMA).
What causes CMA?
Unfortunately, the cause of CMA is not known. We do know it is an immune system response to specific proteins (predominantly cow’s milk). CMA is much more common if there is a family history of asthma/allergies/eczema (also known as atopy). Up to 25% of babies with CMA have a family history of atopy (immune system is more prone to develop allergic reactions or triggers), and half of babies with CMA will themselves also have eczema.