Breastfeeding and Cow's Milk Allergy

Cow’s Milk Allergy (CMA) is the most common food allergy affecting around 2% of UK infants. In breastfed infants the incidence is much lower with a prevalence of around 0.5%1.

It is almost always recommended to continue breastfeeding, even if CMA is suspected, as we know that this is the best nutrition for all infants where possible.  WHO recommend exclusive breastfeeding for the first six months and to continue until two years of age2.  

Below we will discuss the appropriate management of breastfed infants with CMA.

Proteins in breast milk 

It is important to remember that not all breastfed babies will react to the cow’s milk proteins, specifically beta-lactoglobulins, in breast milk. The amount of milk proteins present in breast milk is 100,000 times lower than in cow’s milk. Some infants may only react when they ingest cow’s milk proteins in their own diet either through a standard infant formula or on weaning with solids containing ‘dairy’ (which is used as shorthand for Cow’s Milk Protein (CMP), but often confused with lactose (the sugar found in milk) and even eggs - unrelated to cows, but also found on farms).

Soya and egg proteins can also be found in breast milk and can lead to similar reactions. These are less common but are important to consider if CMA is suspected and there is no clear improvement, or limited improvement on the milk free diet.  Careful management of the mother’s diet is needed with any dietary exclusion.

Cow’s Milk Allergy symptoms when breastfeeding

Common symptoms seen in breastfed babies are mild or moderate and may include eczema and/or diarrhoea, which can sometimes contain blood and mucous. Severe reactions are rare, and it is thought that this is due to breast milk containing secretory immunoglobulin A which is unique to breast milk and helps protect the baby from potential allergens being penetrated through the intestinal wall.

Symptoms usually present soon after breastfeeding commences or when a cow’s milk formula and/or weaning foods containing dairy are given.

Breastfeeding and Cow’s Milk Allergy assessment

Dietary elimination

If there is suspicion that an infant is reacting to the cow’s milk proteins in breastmilk, then strict maternal dietary elimination is indicated for 2 – 4 weeks. 

Taking a diet history can help direct the nutrition advice by finding suitable milk-free alternatives to ensure the dietary prescription of a milk free diet is personalised.  The increasing availability of a wide range of plant-based products in the supermarket means there is a much better choice that are easily accessible and more affordable than in previous years.


Confirming the diagnosis

After the 2- 4 week maternal elimination period it is crucial to confirm the diagnosis or otherwise to avoid an unnecessary and protracted diet that increases the nutritional risk for the mother3.

Cow’s milk and cow’s milk containing foods should be slowly reintroduced into the mother’s diet over a one-week period. 

It is helpful to use a food symptom diary to track any changes in the infant.  Allergy UK have a useful resource and can be found here.

If any symptoms return, the reintroduction of cow’s milk into the mother’s diet should stop and a milk free diet should resume.  A milk free diet is then recommended until the baby is 9 – 12 months of age and for at least 6 months.  Milk free weaning will need to be discussed. 

If there has been no change during the elimination period and reintroduction, then cow’s milk and cow’s milk products can be returned into the mother’s diet, and a diagnosis of CMA is unlikely.

In some cases, symptoms of CMA may appear when larger amounts of milk proteins are given.  This may be if a standard infant formula is commenced or on weaning when milk containing products are given.  The child will then need to go through the same exclusion and reintroduction but using either formula or foods depending on the age of the child.

A complete soya exclusion may need to be reviewed and egg if there is ongoing suspicion of a food allergy, but this should be discussed with the team with a clear treatment plan in place.


Breastfeeding with Cow’s Milk Allergy: what to avoid

If a maternal milk free diet is required, the mother will need advice on which foods to avoid including both obvious sources of milk but also products which contain hidden sources of milk protein. These can include:

  • Margarine
  • Cakes
  • Biscuits
  • Some breakfast cereals
  • Bread
  • Pastry
  • Ready-made meals or sauces
  • Instant custard, potato, or soup.

Lactose-free milk, cheese and yogurts are not suitable as they still contain cow’s milk protein.

It is important to identify a milk alternative that contains both calcium and iodine as well as discuss examples of milk free spreads, yogurts, and cheese.  It is worth considering avoiding replacement with soya products during the trial as the proteins are similar to cow’s milk proteins and some babies may cross-react to them too. A small amount of soya found in certain brands of bread is usually not an issue, but this should be discussed with the team.

Cow’s Milk Allergy diet for breastfeeding

Providing guidance on amounts of milk alternatives, yogurt, and cheese to meet calcium and iodine requirements is important. There is usually around 120mg calcium in 100mls milk alternative or 100g dairy free yogurt.

Many of the cheese alternatives readily available are not fortified with calcium and some only contain small amounts and so it is important to highlight this to avoid confusion with calcium requirements.

It is helpful to discuss meals and how to use dairy alternatives to replace the dairy components of recipes. This is to enable family meals to be made and avoid separate meals being prepared that will increase workload and time for the family whilst on the elimination diet. Additional support from family and friends can be helpful during this time.

Due to increased energy requirements whilst breastfeeding, it is useful to provide examples of suitable snacks.

It is important to show families how to check if foods are suitable by talking them through how to read the ingredients list and being able to identify if they are milk free.

Eating out can be challenging and it is recommended to phone ahead and check that they can accommodate a milk-free diet highlighting caution on using soya as a replacement to milk.

Supplementing breastfeeding in an infant with CMA

All breastfed babies should be on vitamin D drops containing 8.5 – 10 mcg from birth.

Breastfeeding mothers need to supplement their diet with 10mcg vitamin D. Due to increased calcium requirements of 1250mg a supplement may be needed in addition to dietary calcium intake from foods.

Benefits of Breastfeeding

There are many benefits of breastfeeding for the infant and mother both in the short and long term. These benefits are widely recognised 5-6. iMAP guidelines have a useful factsheet available for families, with information to support mothers to continue breastfeeding when there is a suspected mild to moderate non-IgE allergy.7

Angharad Banner

Angharad is a highly specialist paediatric dietitian with over 20 years of experience within the NHS and private sector.

  1. A Prospective Study of Cow's Milk Allergy in Exclusively Breast-Fed Infants. Høst A, et al.  Acta Paediatric Sept 1988 77(5) 663-670
  3. Current Guidelines and Future Strategies for the Management of Cow’s Milk Allergy. Vanderplaas Y, et al. Journal of Asthma and Allergy 1243-1256 Vol 14, 2021 https://doi/full/10.2147/JAA.S276992
  4. Epidemiology of food allergy. Venter C, Arshad SH. Pediatr Clin North Am. 2011;58(2):327–349
  5. NHS. Benefits of breastfeeding[internet][cited 2023 June]. Available from Benefits of breastfeeding - NHS (
  6. The Lancet. Breastfeeding series[internet] [cited 2023 June]. Available from
  7. iMAP guidelines. Supporting breastfeeding factsheet. [internet] [cited 2023 June]. Available from

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