What is CMPA?
CMPA stands for Cow’s Milk Protein Allergy. It is an adverse reaction to the β-lactoglobulin protein in cow’s milk, which does not occur in human breast milk. Allergies can be classified as IgE or non-IgE. IgE reactions occur within 2 hours (but often much faster) of exposure to the allergen, whilst non-IgE reactions occur later, within 72 hours of exposure.
Among exclusively breastfed babies the prevalence of CMPA is around 0.5% (1 in 200), compared with 2-7.5% of formula-fed babies. Use of formula, particularly in the early months, increases the risk of CMPA.
Is it the same as lactose intolerance?
CMPA is often confused with lactose intolerance, and it is really important to understand that they are completely different. Lactose is the main sugar in all mammalian milks, including human breast milk. In fact, human breast milk is particularly high in lactose, as it is a vital fuel for the rapid development of the human brain. As such, human babies are not lactose intolerant. There is a rare metabolic disorder called galactosemia, where the body cannot process lactose properly; however, a baby with galactosemia will become very ill very quickly, and therefore this is likely to be recognised soon after birth.
A temporary lactose intolerance may occur following a disturbance to the gut flora, for example, antibiotics or gastroenteritis. In this case, breastfeeding should continue as usual and the normal gut flora will be restored. Breastfed babies or children who are also having solid foods can avoid dairy products for a short period of time if needed.
Older children and adults can be lactose intolerant, as the human body stops producing lactase (the enzyme responsible for processing lactose) after early childhood. People with a Western European lineage are less likely to be lactose intolerant as these populations have a genetic mutation related to the domestication of cattle; populations where dairy forms a minimal part of the diet have higher levels of lactose intolerance as adults.
What are the symptoms?
For an IgE allergy, i.e. an immediate or almost-immediate reaction, potential symptoms include wheezing, hives, swelling and projectile vomiting. For a non-IgE allergy, potential symptoms include eczema, ear infections, gastro-oesophageal reflux disease (GORD). The table below shows other possible symptoms of CMPA; not every baby will show every symptom.
| Organ involvement | Symptoms |
| Gastrointestinal tract | – Frequent regurgitation – Vomiting or diarrhoea – Constipation (with/without perianal rash) – Blood in stool – Iron deficiency anaemia |
| Skin | – Atopic dermatitis – Swelling of lips or eye lids (angio-oedema) – Urticaria unrelated to acute infections, drug intake or other causes |
| Respiratory tract (unrelated to infection) | – Runny nose, otitis media – Chronic cough or wheezing |
| General | – Persistent distress or colic (wailing/irritable for ≥ 3 h per day) at least 3 days/week over a period of > 3 weeks |
What should I do if I think my baby has CMPA?
Some of the symptoms above can have causes other than CMPA. Vomiting, for example, can often be improved by working on a deep latch and a change in feeding position. Similarly, persistent crying can have many causes. As such, it is important to find a breastfeeding counsellor or IBCLC (lactation consultant) initially, who can assess feeding and investigate what might be happening with feeding. Elimination of dairy is often suggested in the case or reflux or colic, but there are lots of other things which should be considered first. You can read more in our reflux and colic blogs.
If improving the feeding does not help, then the next step is to visit your GP for a diagnosis. For a mild, non-IgE allergy, the first step will be for the breastfeeding mother/parent to eliminate all dairy from her diet for 2-4 weeks to see if the baby’s symptoms improve. At a later stage, the mother can consume a small amount of dairy and watch for any reactions in her baby, to confirm. If CMPA is confirmed, guidelines are to continue a dairy-free diet for at least 6 months, until the baby is 9-12 months old. At this point, dairy can be reintroduced using the milk ladder.
For more severe non-IgE, or IgE allergies, a referral to an allergy specialist might be needed depending on the history and situation. For combination-fed babies having formula, if it is not possible to move to exclusive breastfeeding, a specialist formula will need to be prescribed. If the baby has slow weight gain or faltering growth, they may also need a referral to a paediatric dietitian. A dietitian will be able to support you with reintroducing dairy at an appropriate time, via the milk ladder. They may also prescribe calcium and vitamin D supplements for you (as the nursing parent) as your needs are higher while breastfeeding. More information on treatment is available here.
Many children do grow out of CMPA and are able to tolerate dairy as they get older. In the meantime, dairy-free products are increasingly widely available, including cheese, yoghurt, ice cream, biscuits and chocolate (so don’t despair!). However, dairy can be an ingredient in surprising places, so it is important to check food labels carefully. Even a tiny bit can cause a reaction. In the UK, milk must be labelled clearly as an allergen on all products. Some labels state that they “may contain” milk, which usually means they are produced in a factory handling milk and cross-contamination is a possibility. These will need to be avoided in the case of severe allergies.
Useful links
https://cks.nice.org.uk/topics/cows-milk-allergy-in-children/
By Tamzin West, IBCLC and ABM BfC, for BfSI UK
through the eyes of a breastfeeding support group 