When young infants develop vomiting, diarrhea, and fussiness, some of them are diagnosed as having an allergy to cow’s milk protein. When that diagnosis is made, babies on formula have to switch to a specialized formula — and the mothers of breastfeeding babies have to eliminate all dairy from their diets.
The problem is that specialized formulas are very expensive, which can be a real burden for families. And eliminating all dairy from your diet can be very difficult (it’s surprising how many foods have some dairy in them), leading some mothers to stop breastfeeding.
If every baby that was diagnosed with cow’s milk allergy definitely had it, this would be unfortunate but unavoidable. However, many — if not most — of the babies who get this diagnosis don’t have it at all.
The two types of allergy to cow’s milk
There are two kinds of cow’s milk allergy. One of them is mediated through a type of immunoglobulin called IgE, which causes classic food allergy. This kind is easier to diagnose, as children have more classic symptoms of allergy such as rashes, facial swelling, or flushing. There are also blood tests that can help make the diagnosis.
The other kind is not mediated through IgE, and is tougher to diagnose with certainty.
Babies with non-IgE mediated cow’s milk allergy can have various symptoms, such as vomiting, fussiness during or after feeding, diarrhea, or blood in the stool. The problem is that lots of babies without allergy can have vomiting, fussiness, or diarrhea — and there are other reasons why babies might have blood in the stool, including having a small cut in the anus. The only way to definitively diagnose non-IgE mediated allergy is to eliminate all dairy, see if the baby gets better — and then reintroduce dairy again and see if the symptoms come back.
For lots of understandable reasons, many doctors and parents don’t want to do that reintroduction once a baby gets better — but the baby getting better may have nothing to do with the diet