What causes milk protein allergy in babies

What causes milk protein allergy in babies

Cows’ milk allergy can cause a wide range of symptoms, including:

  1. digestive problems – such as stomach ache, vomiting, colic, diarrhoea or constipation
  2. skin reactions – such as a red itchy rash or swelling of the lips, face and around the eyes
  3. hay fever-like symptoms – such as a runny or blocked nose
  4. eczema that does not improve with treatment

Occasionally CMA can cause severe allergic symptoms that come on suddenly, such as swelling in the mouth or throat, wheezing, cough, shortness of breath, and difficult, noisy breathing.

A severe allergic reaction, or anaphylaxis, is a medical emergency – call or go immediately to your local hospital A&E department.


Cows’ milk allergy in babies

Cows’ milk allergy (CMA), also called cows’ milk protein allergy, is one of the most common childhood food allergies. It is estimated to affect around 7% of babies under 1, though most children grow out of it by the age of 5.

CMA typically develops when cows’ milk is first introduced into your baby’s diet either in formula or when your baby starts eating solids.

What causes milk protein allergy in babies

More rarely, it can affect babies who are exclusively breastfed because of cows’ milk from the mother’s diet passing to the baby through breast milk.

There are 2 main types of CMA:

  1. immediate CMA – where symptoms typically start within minutes of having cows’ milk
  2. delayed CMA – where symptoms typically start several hours, or even days, after having cows’ milk


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Sheet final reviewed: 12 July
Next review due: 12 July

Treatment of CMPA includes removing cow’s milk protein from your child’s diet (elimination diet).

Elimination diets are generally started with formulas made from broken-down proteins (hydrolyzed formulas), which are generally more easily digested without an immune reaction.

These formulas work in about 90% of children with CMPA. In some children, it is necessary to use formulas containing the individual building blocks of proteins (amino acids).

In the case of immediate reaction CMPA that causes anaphylaxis (a serious allergic response with swelling, hives, lowered blood pressure, and, in severe cases, shock), the crucial treatment is a medicine called epinephrine. Epinephrine is generally given by an auto-injecting “pen”, or “epi pen”.

Patients with anaphylaxis need to be evaluated and monitored in an emergency room, even if the symptoms improve with epinephrine.

This is because there is a risk of a “second wave” of symptoms occurring after the epinephrine wears off.

In breastfed infants with CMPA, the mom must exclude every dairy and soy products from her diet if she continues to breastfeed, as these proteins may be passed to the baby through breast milk. This may be hard, although a dietitian can assist discover hidden sources of dairy and soy in the diet.

Goat’s or sheep’s milks generally elicit the same reaction as cow’s milk, so using these as a substitute is not likely to improve symptoms. Soy milk also is generally not recommended.

What causes milk protein allergy in babies

Numerous infants will own similar allergic reactions to the proteins in these milks or soy-based formulas.

What is cow’s milk protein allergy?

Cow’s milk protein allergy is an allergic condition which is triggered by drinking cow’s milk or by drinking or eating products made from cow’s milk.

It can cause:

  1. Skin symptoms, such as rashes and eczema
  2. Gut (digestive tract) symptoms, such as feeling ill (nausea), being ill (vomiting) and abdominal (tummy) pain
  3. Breathing (respiratory) symptoms, such as a runny nose and wheezing.

The symptoms are often vague and sometimes it is extremely hard for a definite diagnosis to be made.

Cow’s milk protein allergy occurs in about 7% of babies who own formula milk, but in only about % of exclusively breast-fed babies, who also generally own milder reactions.

Exclusive breast-feeding may also protect babies from developing an allergy to cow’s milk protein after they are weaned.

Cow’s milk protein allergy is more likely in children who own other allergic (or atopic) conditions such as asthma, eczema or hay fever, or if shut family members own those conditions.


Could it be lactose intolerance?

Lactose intolerance is another type of reaction to milk, when the body cannot digest lactose, a natural sugar found in milk.

What causes milk protein allergy in babies

However, this is not an allergy.

Lactose intolerance can be temporary – for example, it can come on for a few days or weeks after a tummy bug.

Symptoms of lactose intolerance include:

  1. vomiting
  2. diarrhoea 
  3. stomach rumbling and pains
  4. wind


Treatment for CMA

If your baby is diagnosed with CMA, you’ll be offered advice by your GP or an allergy specialist on how to manage their allergy. You may also be referred to a dietitian.

Treatment involves removing every cows’ milk from your child’s diet for a period of time.

If your baby is formula-fed, your GP can prescribe special baby formula.

Do not give your kid any other type of milk without first getting medical advice.

If your baby is exclusively breastfed, the mom will be advised to avoid every cows’ milk products.

Your kid should be assessed every 6 to 12 months to see if they own grown out of their allergy.

Read more about cows’ milk allergy.


Treatment for lactose intolerance

Treatment depends on the extent of your child’s intolerance.

What causes milk protein allergy in babies

Some children with lactose intolerance may be capable to own little amounts of dairy products without having symptoms.

Your kid may be referred to a dietitian for specialist advice.

Read more about treatment for lactose intolerance in children.


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What causes milk protein allergy in babies