Having a baby suffering with cows’ milk protein allergy (CMPA) can be a tough and distressing journey, for both parents and baby alike. We enlisted the help of top expert, consultant paediatric gastroenterologist Professor Neil Shah to answer some of our reader questions on CMPA – to help us understand what it is and how best to deal with it. 

What is CMPA in babies and what triggers the painful reactions that we see happening?

There are two types of CMPA: IgE and Non-IgE milk allergy:

The former (IgE) is when we see classical symptoms of breathing problems and rashes.

The latter, non-IgE milk allergy is usually associated with intense pain. In these children the cause of the pain is still uncertain. The cause of the pain and inconsolable crying which is very distressing for parents to watch in non-IgE mediated allergy children has not been pinpointed; reflux is one factor, but there is also painful passage of wind, straining with stools, abdominal crunching and back arching.

With non IgE, what is known, there is a close proximity of the immune system (your gut is your biggest immune organ in your body) with gut pain fibres (your gut is the second biggest nervous system) that communicate with each other, and this interaction can lead to the intense pain in CMPA, but there is a still a lot more to learn about why CMPA is so painful.

What are the symptoms of CMPA and what are the typical solutions and medications we can expect to be offered to help?

Immediate type IgE-mediated CMPA – symptoms occur within a few hours:

  • skin reactions
  • itching
  • swelling of lips, face, eyes,
  • breathing issues
  • abdominal pain
  • vomiting
  • diarrhea
  • sneezing
  • itching, runny or blocked nose

Delayed reaction Non-IgE mediated CMPA – symptoms can take days if not weeks to present:

  • reflux
  • colic
  • eczema
  • sore red bottom
  • abdominal pain
  • constipation
  • loose or frequent stools
  • blood and /or mucus in stools
  • Faltering Growth in some children

Generally, if it’s a milk allergy, changing the milk is the main step. Medications can help once the milks have been changed with residual symptoms e.g. pain and reflux.

What is the typical age to develop CMPA and why is it seemingly so hard to diagnose?

The most common age is under a year. The majority are diagnosed under six months and often most parents notice things not being quite right at a very early age – sometimes weeks. Because it’s also a time that colic, regurgitation and posseting are common in babies, it can be difficult and confusing to diagnose.

What’s the difference between a cows’ milk allergy and a lactose allergy and how do you know which is the one baby is suffering from? Is it largely trial and error?

Lactose is the sugar present in milk. Congenital lactose intolerance is very, very rare. Breast milk contains more lactose per ml than cows’ milk, and so from an evolutionary point of view it would not make sense to have a baby intolerant to lactose.

More commonly babies can become temporarily intolerant to lactose, following gastroenteritis. It is not immune mediated. It is very common to mistake CMPA and diagnose it as lactose intolerance. The problem with this is lacto free formula still contains cows’ milk, so is not appropriate to treat babies with CMPA.

My simple rule is if there is no history of infection, I wouldn’t diagnose lactose intolerance in babies. A good clinical history is key in diagnosis. Cows’ milk allergy is immune mediated and it is a different part of the milk – the protein, which causes the symptoms that you see.

It can be confusing to know which type of CMPA is causing the issue as some of the symptoms overlap, however, looking at the clinical and allergy focused history can give an indication.

For immediate type (IgE) allergy testing can be useful.

For delayed reaction (non-IgE) unfortunately there are currently no specific tests but occasionally allergy tests can help define the type of milk allergy and also identify other foods that a child may react to when weaned. Dairy exclusion and then reintroduction producing replication of symptoms is gold standard for diagnosis, although this often proves difficult as parents find it distressing and are often reluctant to re-challenge their babies once they have had symptom improvement with dairy exclusion.

Does it take time to develop an allergy? My daughter was around three weeks / a month old when her symptoms fully developed, and we realised we had a problem on our hands.

Yes, recognition is commonly difficult and realisation can depend on symptoms – e.g. blood in stools is easier to recognise as a symptom of CMPA than excessive screaming.

Symptoms become progressively worse and less confusing as babies get older. Babies can display colic symptoms when only a few weeks of age which is normal, but the persistence of these symptoms and a failure to respond to treatment such as anti-reflux medicines, can alert doctors and parents that something else is going on. Recognition can take many months and several GP visits which can be very frustrating.

Is a baby more likely to develop CMPA on formula as opposed to breast milk, even is mum isn’t dairy free

CMPA can occur in exclusive breastfeeding with a rate of around 0.5-1%. It’s often easier when switched to mixed feeding or start an infant formula made from cows’ milk where the rates are higher but are still imprecise but around 3% .

The focus is always first to change a mother’s diet to diary and soya free, and to try and maintain breastfeeding. Often by the time I see these children mum has given up breastfeeding, which is very sad.

Does what I eat during pregnancy have any affect on whether my child will have CMPA?

No, there are no associations or preventative measures that we know of before birth, although we know CMPA rates are higher in C-section babies. There is often a family history of allergy but not always . Why some babies and not others get CMPA is still poorly understood. Environmental factors and gut bacteria patterns called the microbiome are all important, but today our main tasks are not only to improve and recognition, but identifying the triggers and ways to speed recovery. The ideal would be to prevent the problem happening in the first place but we are a long way away from that at the moment.

It seems to affect so many children. If your first baby suffers from CMPA, is your second baby likely to?

It is common in families to have more than one child affected by CMPA and we do have families with several members affected, but it’s not an absolute. Some children have no problems despite having several siblings with the allergy.

If you know your first baby suffered from CMPA, is it best just to remove dairy from your diet during pregnancy, or after birth so that your breast milk is dairy free for any future children?

My preference is waiting to see if your baby develops symptoms consistent with milk allergy rather than starting a restricted diet, as your child may have no illness or symptoms consistent with milk allergy, so you may be creating a problem where there is none.

There is also no evidence that removing milk before birth will work and may be counterproductive; limiting the mother’s diet is a nutritional risk for a baby that is otherwise completely healthy.

Why does CMPA seem to go hand in hand with reflux? Is reflux simply the body’s way of trying to eject the milk that’s causing problems?

Vomiting is reflux that you can see, and can be normal for babies. Usually it’s very mild and in small volumes if , but it can also be a reflex that protects us when we ingest noxious substances. Reflux can be driven by milk protein and removing dairy can resolve reflux partially or completely in some children or make them much less troublesome to a point where the majority of babies no longer need treating.

How likely is it that my baby will grow out of this, and why is that possible, what age is most common, and how many babies go on to have this intolerance into childhood and adulthood?

The belief held is that most children grow out of cows’ milk allergy within the first year of life. In reality, most children do grow out of their cows’ milk allergy but between the ages of 2-3 years. In my experience, many infants do begin to acquire some tolerance to milk before a year, and can tolerate it in baked or heated forms, but not raw. Tolerance to raw milk is often seen much later, around 2-3 years, so cows’ milk allergy is longer lived than most people think.

My baby supposedly has CMPA, but it’s only at night-time he screams and itches his face so badly. Can this be an allergy to milk, and if so, why is the night-time worse for allergies?

Eczema is a common association with CMPA, and it’s true, lots of night symptoms can occur and we don’t really understand why infants can be worse at night. This may be related to the transit of digested foods to the lower intestine (painful wind is common) but it can be one of the most disturbing and exhausting symptoms for families.

Is it possible to develop an allergy over a milk that was previously helping?

This is called a loss of response and is reported in up to 30% of babies with non-IgE mediated allergies. These milks are called extensively hydrolysed formulas and if very symptomatic it would mean a switch to another group of specialist formulae called amino acid milks.

The ongoing symptoms when on an extensively hydrolysed formula needs to be judged carefully as colds, inter-current viruses and teething may all look like the milk is failing, when in fact, symptoms are being triggered by other factors happening at the same time.

What is the ‘milk ladder’ and how does weaning differ to that of a baby without intolerances?

The milk ladder concept was invented by two leading dietitians and is based on the idea that milk when presenting to the body can be modified by baking or heating rather than given in its more raw form. The idea is that over time, this slow introduction approach will coax the child in becoming tolerant to the milk. It is important to say this is only applicable to non-IgE CMPA not an anaphylaxis type allergy, and vital not to use it in the latter allergy.

Is CMPA a relatively new phenomenon, or did our parents and grandparents suffer just as much when they were babies?

CMPA has been around for thousands of years, but why it’s increased and recognised better now is not clear, but the way we eat, are born, and how we expose our bodies to foods, use or over use of antibiotics and many other factors can be important to explain why CMPA and many other allergies are seen in increasing numbers in the UK and worldwide nowadays.

Professor Neil Shah, 
Consultant Paediatric Gastroenterologist, MD MRCP(UK)
The Portland Hospital 215 Great Portland Street LONDON W1W 5PN

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