Tests for Cow’s milk (protein) allergy

Baby feeding from a bottle in their Monther's arms

I get asked this very often when I diagnose CMPA in a baby. The most common type of CMPA is Non IgE mediated. It presents at the age of 4-6 weeks onwards. The symptoms are dry skin, reflux (unsettled, vomity baby), runny stools or worsening constipation. Some babies are also snuffly and have blocked nose, all the time.

The severe form, which is IgE mediated CMPA, presents earlier, within days as vomit as soon as milk is given (usually formula), sneezes, rash over face and sometimes breathing difficulty. This can be diagnosed with a blood test (specific IgE for milk) or a skin prick test to milk. Fortunately, this is much less common than Non IgE mediated cases.

There is no test for the Non IgE mediated CMPA as IgE (Immunoglobulin E) is not involved in the allergy. It is still a true allergy. The good thing is that children with this condition grow out of it between the age of 1 to 2 years. (IgE mediated CMPA may persist for 7-8 years or even longer).

The best test is going dairy free (if you are breast feeding) or giving a special (Extensively Hydrolysed) formula, which is on prescription (Aptamil Pepti, Nutramigen or Similac Alimentum). They all taste bad but the babies get used to it pretty quickly as their taste buds are not very well developed. It may take 2-4 weeks before you see marked improvement in symptoms.

Then at 4 weeks, you reintroduce the dairy in babies or mother’s diet.

If symptoms return – It confirms CMPA and you should go back to ‘dairy free diet’

If they don’t – It possibly was not CMPA and you can relax !

See: https://www.allergyuk.org/about-allergy/allergy-in-childhood/cows-milk-allergy/