Your child’s doctor will be able to lead you through the steps to diagnosis. He or she will use the information about your child’s symptoms and medical history to decide whether allergy tests are appropriate and, if so, which type of test would be suitable. This depends partly on the type of allergy suspected. The first step would be to eliminate the food to blame from your or your child’s diet; this will depend on the following:
Are you still breastfeeding?
Clinical guidelines recommend that breast feeding is continued if there is a suspicion of CMA in your breast-fed baby as this has benefits, though it is advised that you as a mother need to eliminate cow's milk protein from your diet for 2-4 weeks.
Is your baby formula fed?
Your child’s doctor will recommend starting feeding your infant an alternative formula. Options for formula substitutes available range from formulas containing cow’s milk proteins which have been broken down to formulas that contain no cow's milk protein at all, so-called amino acid-based formulas.
Does your child already eat solids?
When your child is on solids and your doctor is suggesting starting an elimination diet as he or she suspects CMA all cow’s milk products should be eliminated from the diet. During this time breast or formula milk continues to play a fundamental role as a source of nutrition whilst your baby adjusts to a mixed diet.
After 2 to 4 weeks a follow-up visit should be planned. If the symptoms have disappeared, the doctor will go one step further in the diagnostic process and perform some additional tests. Further allergy testing involves for example skin tests, blood tests or a food challenge. The type of test chosen depends on the type of the allergic reaction. For example, skin or blood tests would be performed in the case of early onset symptoms such as skin rash or swelling.
Symptoms such as eczema, diarrhoea or blood in stools can also appear several hours or days after the food is eaten, eventually even the growth of your child could be affected. Unfortunately, some children show mixed reactions. For late onset food allergies the doctor would recommend to reintroduce cow’s milk in your child’s diet in very small doses to see whether the symptoms return. This procedure is called “oral food challenge”. The first step is to decide whether the test can be performed at home or if it needs to be under direct paediatric supervision. There are many specific issues that must be considered in order to reach this particular decision. Your child’s doctor will inform you of all the ins and outs.
(National Institute for Health and Clinical Excellence. 2011)