Elimination and challenge

Elimination and challenge

In cow's milk allergy (CMA) the immune system mistakenly identifies a protein in cow's milk as harmful and triggers an allergic reaction. This leads to a range of symptoms that can vary in type, severity and time of onset from baby to baby.

The symptoms of CMA and the severity of the reactions are wide ranging. They can include colic, skin reactions (such as a red itchy rash, eczema or swelling of the lips, face and around the eyes), digestive problems (such as vomiting, abdominal pain or diarrhoea) and hay fever-like symptoms (such as sneezing or itchy, blocked or runny nose). Symptoms can range from mild to severe reactions.

These symptoms can either appear immediately after consuming dairy (within minutes or up to a few hours) or may be delayed, taking a few hours or up to a few days to develop. Babies with CMA may have a mixture of both 'immediate' (usually IgE-mediated) and 'delayed' (usually non-IgE-mediated) symptoms. Symptoms may also lead to night-time waking, crying or distress during feeding, or poor weight gain. Find out more about the different types of cow’s milk allergy.

As part of the diagnosis process your doctor may have suggested putting your baby on an elimination diet followed by a food challenge. If your doctor suspected that your baby’s cow’s milk allergy was IgE-mediated they may also have recommended a skin prick or blood test.

Elimination diet

An elimination diet involves removing cow’s milk protein from your baby’s diet for a short period of time, and then monitoring the effect this has on their symptoms. If you’re breastfeeding, this means removing foods containing cow’s milk protein from your own diet. If you’re formula feeding, this means switching your baby onto a special hypoallergenic formula recommended by your doctor that is designed for babies with cow’s milk allergy. Your doctor, health visitor or a dietitian will have advised you on how to begin the elimination diet and how long to continue for. A trial up to 4 weeks is usually given.

Remember, it is important to be vigilant with checking all other food that is consumed by your baby for any hidden sources of cow’s milk. Reading packaging labels and ingredient lists is a must and they will often highlight the presence of milk.

Now that your doctor has recommended a hypoallergenic formula as part of an elimination diet, this won’t contain whole cow’s milk protein so in most cases should no longer be recognised by the immune system as harmful. It may be an extensively hydrolysed or an amino acid-based formula. Extensively hydrolysed hypoallergenic formulas are effective in approximately 90% of infants with cow's milk allergy. If your child has severe or multiple food allergies or their symptoms did not resolve after trying an extensively hydrolysed formula for a trial period, your doctor may recommended an amino acid-based formula. Find out more about these formulas in what diet changes are needed. You should follow your doctor’s guidance and continue with the recommended dietary management until you are advised otherwise by a healthcare professional.

Food challenge

After your baby has been on a cow’s milk protein-free diet for a few weeks and symptoms have clearly improved, your doctor may recommend an ‘oral food challenge’. This involves feeding your baby a small amount of a milk-based product and carefully watching for any signs of reactions. This process may take place at your doctor’s surgery or hospital clinic, or your doctor may ask you to gradually reintroduce routine cow’s milk-based infant formula into your baby’s diet at home while you note any changes. It’s important that you only do this with the advice and supervision of a healthcare professional.

If an allergic reaction isn’t seen at the time of the challenge or later on, your doctor will investigate other possible causes of your baby’s symptoms, such as colic or lactose intolerance. If an allergic reaction is seen, the diagnosis of cow’s milk allergy can be made. You will then need to keep your baby on the elimination diet until they grow out of their allergy. Your doctor will advise you when to try another food challenge to see whether they have grown out of the allergy and can return to a normal diet

Now that your baby has been diagnosed with cow’s milk allergy, find out about managing and living with cow’s milk allergy to help you care for them.

Some of these symptoms can also occur for reasons other than CMA, so it is important to discuss them fully with your doctor.


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