Skin tests are often the starting point because they are quick to do. If your child has an immediate reaction after eating, skin or blood tests are much more likely to be positive. If the symptoms of the allergy typically appear hours or even a day or two later, then it may not show on skin or blood tests. Of course, this type of allergy test is just one part of the diagnosis process – sometimes the results (both positive or negative) can be wrong. That means that your child can show allergy symptoms in spite of the test saying he or she is not allergic.

Skin Prick Tests are especially accurate in testing for cows’ milk allergy. Small drops of cow’s milk (or other foods which are suspected) are placed on the child’s forearm. A small prick is made through each drop into the skin. If the child’s skin becomes red and itchy, it usually means that he or she is allergic to that particular food. This is called a positive reaction. If no reaction is shown in the test, there is still a chance your child has a food allergy. This can happen if your child shows a delayed reaction after food intake, a so-called non-IgE reaction.

Skin Prick Tests are quick. So they are often used as first tests to find which foods cause reactions. Once the allergens are identified, some doctors may perform more specific tests (these are known to doctors as Specific IgE tests or RAST test).

Specific IgE tests are blood tests that can measure the concentration of specific antibodies in your child’s blood. These antibodies are called IgE. IgE levels in the blood are often higher in children who have allergies or asthma. If the test is negative, it is still possible that your child has a food allergy, but in this case it is known as a non-IgE or delayed reaction.

If allergic reactions happen hours or days after the food is eaten. These diets may require elimination of certain foods or specific food challenges.

An elimination diet may be recommended by your child’s Doctor or Dietitian in order to prove that your child reacts to foods such as cows’ milk, eggs, wheat, or soya. With the results from this elimination diet, the medical history of your child, (blood tests - not always required) as well as the food and symptom diary, your Doctor will have more to work on when trying to reach a diagnosis.

Under the strict supervision of your child’s Doctor or Dietitian, the food suspected to cause the trouble will be eliminated from your baby’s diet e.g. cow's milk for about two to six weeks. It is important that you avoid all foods that contain the relevant trigger; your child’s Doctor or Dietitian will give you precise instructions on how to do this. To feed your child adequately during an elimination diet, a special cows’ milk protein-free infant formula is likely to be prescribed. This may be an extensively hydrolysed formula (eHF) or an amino acid-based formula (AAF).

Following an elimination diet your child’s Doctor or Dietitian will encourage you to undertake a ‘food challenge’ if they still need to confirm a diagnosis. This occurs in non-IgE or delayed reaction allergies.

If your child is suspected of having a Cow's Milk Allergy and symptoms improved or resolved when cow's milk was removed from your child'd diet, if you then reintroduce cow's milk and your child has a reaction this confirms the diagnosis. Ensure you always follow the advice of your Doctor or Dietitian.

Other food challenges may occur if your Doctor or Dietitian suspects that your child may have outgrown their allergy or they are no longer as sensitive e.g. they can tolerate a very small amount of the allergen or they can tolerate the allergen in a different form e.g. a baked cake that contains milk.

If you are doing a food challenge to see if your child is still allergic, very small amounts of an allergen may be given onto the juices, pureed foods or cooked dishes depending on the age of the child. Depending on the severity of your child's allergy depends on where and how the food challenge is conducted. It may be in a hospital, in a Doctor's clinic or at home with advice provided by your Doctor or Dietitian.

Challenge tests should be supervised by your child’s doctor or dietitian and are best conducted in a clinic or hospital setting with qualified personnel and equipment. Always follow your Doctor or Dietitian's advice when completing a food challenge.