Description and symptoms of cow’s milk protein allergy

In a baby with CMPA, milk proteins that should normally be well tolerated are identified as undesirable, triggering an immunological reaction.
The bigger the proteins, the more likely they are to cause an allergy. In the majority of infant formulas aimed at babies with CMPA, the proteins are hydrolysed (divided).
In a baby allergic to milk proteins, the proteins found in cow’s, goat’s and sheep’s milk all cause an immunological reaction. This can result in a very wide variety of symptoms, which can occur immediately after ingestion of the proteins or up to a week a later:
- Skin signs (redness, itching, swelling), which occur in 50% of CMPA babies (1);
- Gastrointestinal signs (regurgitation, vomiting, colic, etc.), which occur in 25 to 50% of CMPA babies (1);
- Respiratory signs (wheezing, asthma, etc.), which are rarer (1).

The two types of CMPA

IgEs or immunoglobulin E are antibodies produced during an allergic reaction. They play an important role in immunological complications. Accordingly, there are two types of cow’s milk protein allergy:
- IgE-mediated: with the production of IgE antibodies, which concerns 60% of cases
- Non IgE-mediated: without the production of IgE antibodies, which concerns 40% of cases
The symptoms differ depending on the type of allergy:

Cow’s milk protein allergy and lactose intolerance: two very different conditions

CMPA and lactose intolerance are often confused but they are actually very different things. Allergy concerns an immune reaction against the proteins contained in milk while intolerance to lactose (a sugar contained in milk) concerns the inability of the digestive system to digest it.
However, when a baby has CMPA, it is nonetheless preferable to avoid giving him lactose, since this may contain tiny amounts of cow’s milk proteins that could trigger an immunological reaction. So it’s best to avoid foods that contain lactose.