Over-Diagnosis and Under-Diagnosis are common.

What is Cow’s milk allergy, and what are the symptoms?

Cow’s milk allergy affects around 1 in 20 babies under 1 year of age.

Cow’s milk allergy is an immune reaction to proteins in milk. This is the milk that normal formula milk is based on (cow’s milk formula). It can also occur in breast-fed babies (when the baby is allergic to cow’s milk through the mother’s diet).

There are two types called “IgE mediated (IgEm)  and “non IgE mediated” (non-IgE).

IgEm causes an allergic reaction within 20 minutes of having the milk (such as a hives-type rash with itchy red skin, swelling of the face or lips, tummy pains, vomiting, diarrhoea). There can also be respiratory symptoms (wheeze, hayfever type symptoms). It is usually fairly obvious that these symptoms come on soon after a bottle / milk feed. The other name for this is the immediate type of cows milk allergy.

Non-IgEm causes symptoms later on so that the symptoms do not appear related to the last feed. Symptoms may include Eczema, red skin, itching, vomiting up milk, loose bowel motions, abdominal pains, colic, constipation (only occasionally), and perianal redness. The other name for this type of cows milk allergy is the delayed type.

So the main difference between the two types is that the first causes sudden symptoms that start and stop soon after feeds, whereas the second causes continuous symptoms that are not obviously related to feeds. The delayed type is much harder to diagnose than the immediate type because the symptoms do not immediately correlate with the last feed.

How can you tell whether a baby with eczema has cow’s milk allergy? The more severe and eczema and the younger the age it started (Starting by 6 months of age), the more likely it’s caused by cow’s milk allergy. Also, an infant with both eczema and vomiting is more likely to have cow’s milk allergy than an infant with just eczema or just vomiting. But there are no “absolutes.”

What Tests are there for cow’s milk allergy?

There is an allergy test for the immediate type but not the delayed type. About half of those who test positive for the cow’s milk allergy actually have symptoms caused by the cows milk allergy.

There is no pathology test for delayed cow’s milk allergy. The test is a strict elimination of cows milk for up to 8 weeks – by using a specific speciality formula milk.

Which speciality formula should I use?

It’s best to go to the manufacturer’s website for their latest products. Aptamil, for example. For mild to moderate cow’s milk intolerance, you can use Aptamil gold + AllerPro1 (under 6 months) and the AllerPro2 for over 6 months, and for the immediate type use aptamil gold pepti junior (0-6 months). You can buy these from a pharmacy without prescription. It should be emphasized that you need to discuss the plan fully with your GP.

What is the role for soya milk?

Soya milk should be avoided under 6 months of age because they contain small amounts of isoflavins that have a weak hormonal effect. There is some cross-reaction between soya proteins and cow’s milk proteins so that some will be allergic to both. The speciality formulas contain all the nutrients that a baby will need.

How quickly should symptoms improve on the exclusion diet?

Most symptoms will usually resolve within 4 weeks of a cow’s milk elimination diet.

How long should the exclusion continue, and when do children outgrow the allergy?

This depends on the type of allergy. The delayed type usually sorts itself out by 2.5 years of age (by then, most are cow’s milk tolerant). A challenge can be done every 6 months from the age of 1 year .

The immediate type lasts longer with just over half outgrowing their milk allergy by age 5. Tolerance is assessed using allergy tests.

Should I see a dietician?

There is some evidence that some babies and infants on the exclusion are more likely to be malnourished or obese. Your GP may advise that you see a dietician.

1: Agostoni C etal; east-feeding: a commentary by the ESPGHAN committee on nutrition. J PediatrGastroenterol Nutr 2009;49:112-25

WRITTEN BY: Dr Richard Beatty