What is cow's milk allergy?

Cow’s milk allergy, or dairy allergy, is the most common type of food allergy in infants and young children in the UK. It happens when the immune system identifies a protein within the cow’s milk as harmful, and triggers an allergic reaction. This leads to symptoms that can either occur immediately (within minutes) or be delayed for anything up to a few days after consuming dairy or foods containing cow’s milk protein.

On this page you’ll find the answers to all your initial questions about cow’s milk allergy.

Which foods contain Cow's milk protein?

Is it cow's milk allergy?

What are the symptoms?

Cow’s milk allergy can give a wide range of signs and symptoms. These may include colic, skin reactions (e.g. a red itchy rash, swelling of the lips, face and around the eyes or eczema), digestive problems (e.g. abdominal pain, vomiting or diarrhoea), and hay fever-like symptoms (e.g. sneezing or itchy, runny or blocked nose).

The exact symptoms vary from baby to baby, and can depend on whether they have an IgE-mediated or non-IgE-mediated allergic reaction. Find out more about the symptoms of cow's milk allergy.

Why does an allergic reaction happen?

The allergic reaction happens because the immune system mistakes the proteins in cow’s milk to be a threat, when in fact they should be harmless. It then releases chemicals such as histamines and others – it’s these chemicals that trigger the signs and symptoms of an allergic reaction.

Is it common?

Yes – many babies are allergic to cow’s milk protein. In fact, cow’s milk allergy is the most common type of food allergy in infants and young children, affecting around 2–7.5% of infants.2

Good to know
In a survey of 1,649 mums1, 78 (5%) had a child diagnosed with cow’s milk allergy, and a further 64 (4%) strongly suspected their child had cow’s milk allergy but hadn’t yet had a diagnosis.

This means that if your baby is allergic to cow’s milk protein – you’re not alone! There is information and support available from your healthcare professionals, charities and organisations, other parents like you, and online. Take a look at our Resources section to find sources of information and support available. See what TV mum Jennifer Ellison has to say about her experience of having a baby with cow’s milk allergy.

Who gets it?

Cow’s milk allergy tends to develop within an infant’s first year of life. Most will grow out of it as they get older, on average by 3–5 years of age.

Experts aren’t sure why some babies become allergic to cow’s milk protein. What they do know is that your baby has a higher risk of cow’s milk allergy if there’s a family history of allergies such as asthma, eczema or a food allergy.

How do I find out if my baby has cow’s milk allergy?

“Find other parents who have children with CMA and chat to them!”

Mum of a child with CMA1

It’s not always easy to tell if your baby has cow’s milk allergy, as the symptoms might not be that clear or they could be caused by other things. If you suspect that your baby might be allergic to cow’s milk protein, speak to your doctor, who may investigate further or refer your baby to a specialist.  To find out more download:

CMA Questionnaire

Symptoms Diary

How is cow’s milk allergy managed?

If your baby has cow’s milk allergy, you’ll need to remove cow’s milk protein from their diet to see improvement in the symptoms. If you’re breastfeeding, this means removing cow’s milk protein or dairy products from your own diet, as this could be passed to your baby through your breast milk.

If you’re bottle feeding, you’ll need to switch your baby onto a special hypoallergenic baby formula designed for infants with cow’s milk allergy. It’s important that you only put your baby onto a dairy-free diet under the advice and supervision of a healthcare professional.

Good to know
In our survey,1 out of the 142 children with diagnosed or suspected cow’s milk allergy, 52 (37%) had a parent who also had a food allergy, and 57 (40%) had a sibling with a food allergy. 

Are babies with cow’s milk allergy allergic to other foods too?

Babies with cow’s milk allergy could be allergic to goat’s and sheep’s milk, as the proteins in these milks are almost identical to each other. These milks are therefore not recommended for babies who are allergic to cow’s milk protein.

Babies with cow’s milk allergy might also be allergic to other non-dairy foods like egg, peanut, tree nuts, soya, wheat, shellfish and fish. If your baby is allergic to cow’s milk protein, speak to your healthcare professional before introducing them to these foods.

Is cow’s milk allergy the same as lactose intolerance?

Cow’s milk allergy and lactose intolerance are often confused with each other, but they are not the same. Cow’s milk allergy is where the immune system launches an allergic reaction to the protein in cow’s milk, whereas lactose intolerance is where the digestive system is unable to digest the sugar (called lactose) in milk.