Cows' milk allergy

Also called cows' milk protein allergy (CMPA) or dairy allergy

Cows' milk allergy (CMA) occurs when your baby’s immune system reacts to the protein in cows' milk.

On this page, you can find the following information:

Key points

  1. Recognising CMA is not always easy because babies can have a range of symptoms. However, making the correct diagnosis is important. Don't guess. See your doctor – there are downsides to unnecessarily removing food from your own or your infant’s diet. 
  2. Not all symptoms arising after having cows' milk are due to allergy. For example, some people are intolerant of lactose, a natural sugar in cows' milk. This is usually seen after the age of 2 years. Read more about cows' milk allergy or lactose intolerance.  
  3. If your child is diagnosed with CMA, you may need to completely eliminate cows' milk (and therefore dairy products) and any foods with cows' milk-containing ingredients from your baby's diet.
  4. Some mothers may need to avoid cows' milk and dairy products while breastfeeding. Some infants and children with CMA can have dairy especially where it is a minor ingredient in a well-cooked food – your doctor or dietitian can help decide if this is true for your child. 
  5. If your baby is formula fed, it's important to choose the correct type of non-cows' milk formula. Read more about infant formula for cows' milk allergy.
  6. Most children will outgrow CMA by school age, and many in earlier childhood.  

What is cows' milk allergy (CMA)?

Cows' milk allergy (CMA) occurs when your baby’s immune system reacts to the protein in cows' milk. The body's immune system fights off harmful bugs and infections. The immune system of babies with CMA identifies the protein in cows' milk as being harmful. This produces an allergic response, which can present as a wide range of symptoms (see below). 

Cows' milk contains 2 types of protein – casein (which is the curd formed when milk turns sour) and whey (which is the watery part left when the curd is removed). Your baby may be allergic to one or both of these proteins.

How common is CMA?

CMA is a common childhood allergy, affecting 2–3% of children (ie, up to 3 in every 100 children) before the age of 3 years. Babies who have close family members (parent, brother or sister) with allergic conditions such as eczema and asthma are more likely to have CMA.

CMA is less likely in babies who are only breastfed, as their only source of cows' milk protein comes through their mother's diet. This is associated with a lower risk of allergy. 

What are the symptoms of CMA?

The symptoms of CMA depends on the type of allergy. There are 2 main types of CMA: IgE-mediated CMA and non-IgE-mediated CMA. 

IgE-mediated CMA

In this allergic reaction, the immune system produces IgE antibodies that cause the release of chemicals such as histamines. This triggers an immediate allergic reaction. The symptoms appear within minutes or up to 2 hours after having anything that contains cows' milk protein. Your baby's reactions may involve the following symptoms:

  • skin turning red, itchy skin, hives or swelling
  • tummy symptoms such as vomiting, runny poos or tummy pain
  • breathing problems such as noisy, wheezy, fast or difficult breathing, cough or a runny nose
  • getting pale and floppy. 

Severe IgE-mediated allergic reactions are called anaphylaxis. This is a potentially life-threatening allergic reaction that comes on very quickly and affects the breathing (eg, persistent cough, wheeze, difficulty breathing) or heart (pale, floppy, loss of consciousness). Anaphylaxis requires urgent medical help. This type of allergic reaction is uncommon. Babies who have IgE-mediated CMA often have allergies to other foods, such as eggs and peanuts.

If you think your baby is having a serious allergic reaction phone 111 straight away.

Non-IgE-mediated CMA

These allergy symptoms are not due to IgE antibodies. The symptoms usually appear after 2 hours or up to a few days after having food containing cows' milk protein. 

Reactions usually involve tummy symptoms such as vomiting, runny poos, tummy pain or blood in the poos. Skin and breathing symptoms are rare.

Mixed allergic reactions

Some babies with CMA can have mixed allergic reactions, where they have symptoms of both IgE-mediated and non-IgE-mediated allergy. 

How is CMA diagnosed?

Diagnosis of IgE CMA is usually obvious if symptoms occur soon (minutes to hours) after having cows' milk or other dairy foods. This can be confirmed by your doctor after taking a medical history and using allergy tests. Allergy tests (skin or blood tests) can be used to confirm the presence of IgE antibodies. 

The diagnosis of non-IgE delayed allergic reactions is more tricky. This is made by a specialist paediatrician or clinical immunology/allergy specialist. This usually involves excluding cows' milk and other dairy foods from your baby's diet for a trial of 1–4 weeks to check for improvement. Then your doctor would advise you to gradually introduce some cows' milk and other dairy foods to see if the symptoms come back. Some forms of non IgE dairy allergy require more cautious food reintroduction.

How is CMA treated?

If your baby is diagnosed with CMA, you need to cut out cows' milk, dairy products and any foods with cows' milk-containing ingredients from their diet. Some infants and children with cows' milk allergy can have dairy especially where it is a minor ingredient in a well-cooked food – your doctor or dietitian can help decide if this is true for your child.

If your baby is formula fed, you need to give them a non-dairy infant formula. There are 3 main types of non-dairy infant formula: soy-based formula, extensively hydrolysed formula (eHF) and amino acid formula (AAF). The type of infant formula that is best for your baby depends on their age and the type of CMA they have. Ask your doctor or dietitian for advice on which infant formula to try.

Read more about infant formula for cow milk allergy.

Is breastfeeding safe in babies with CMA?

You can continue to breastfeed infants with CMA. Breastfeeding alone is the best source of nutrition for all babies until the age of 6 months. For babies older than 6 months, you need to slowly introduce solids because breastfeeding alone is not enough for growth and development. If possible, babies should continue to be breastfed until they are at least 12 months of age. 

For babies that are breastfed only, mothers should continue breastfeeding. Many women can continue to have cow’s milk or dairy in their own diet without affecting the baby, but some women will also need to avoid but must avoid any foods or drinks that contain cows' milk products or dairy. Your doctor or dietitian can help make this decision. Mothers who are avoiding dairy may need help to make sure they are getting enough calcium.

If this does not resolve symptoms, or if breastfeeding is not possible or adequate, or if you wish to wean your infant before they are aged 12 months, ask your doctor or dietitian for advice on which infant formula to try.

What infant formulas are not suitable for CMA?

There are many other infant formulas available that are not suitable for CMA:

  • Partially hydrolysed formula – the cows' milk protein has been only partially broken down so can still cause an allergy. Examples include Karicare HA and Nan HA Gold Protect.
  • Goat’s milk, sheep milk, mare’s milk – these animal milks are not suitable for children or adults with CMA as the proteins are very similar to those in cows' milk and most people will react to these too.
  • Rice milk, oat milk, almond milk, cashew nut milk, coconut milk – these plant-based milks are lower in energy, protein and fat. Some are fortified with calcium and B vitamins. Rice milk is not recommended for children under 5 years of age as the sole milk replacement because it does not meet their nutritional needs but can be used as a supplement with help and advice from a dietitian. 

Is CMA lifelong?

Most children tend to outgrow their CMA. Babies with non-IgE CMA tend to outgrow the allergy early, with most cases resolving by 1–2 years of age.  Children with IgE CMA may have slower resolution, but many grow out of this by school age. 

It is very important to have a reliable diagnosis by a specialist before re-starting cows' milk, and to seek the advice of a registered dietitian.

Learn more

Cow's milk allergy Allergy NZ
Reflux in infants Health Navigator NZ
Infant colic Health Navigator NZ


  1. Managing cows’ milk protein allergy in infants BPAC, NZ, 2019
  2. Cow's milk (dairy) allergy Australasian Society of Clinical Immunology and Allergy, 2019
Credits: Health Navigator Editorial Team. Reviewed By: Dr Jan Sinclair, Paediatric Allergy and Clinical Immunology, Starship, Auckland Last reviewed: 11 Mar 2020