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How to spot symptoms of Cow’s Milk Allergy in babies
What is Cow’s Milk Allergy?
When a baby has a Cow’s Milk Allergy (CMA), sometimes known as cow’s milk protein allergy, their immune system overreacts to the proteins found in cow’s milk, causing mild or severe symptoms of an allergic reaction. CMA is not the same as lactose intolerance, which is rare in babies and involves a digestive issue rather than an immune issue.
CMA usually occurs in the first year of life, when a baby is:1
- introduced to formula containing cow’s milk (common)
- exclusively breastfed/chestfed, where the proteins from cow’s milk can pass into the breastmilk (human milk) from the mum’s/feeding parent’s diet (rare)
- weaning onto cow’s milk-based products, such as yoghurt, or cow’s milk in food
The good news for families is that most babies will outgrow their CMA.
Why early detection matters
Babies grow rapidly in their first year of life, and good nutrition is important. Cow’s milk is an important source of energy, protein, vitamins and minerals.
Babies with CMA are more vulnerable to nutritional and growth problems, as well as feeding and sleeping issues due to the discomfort from their symptoms. If CMA is not properly diagnosed and managed, these problems may escalate.2
Common signs and symptoms of cow’s milk allergy
Symptoms of CMA can be wide-ranging, but most babies will not experience all of them. They may not look like classic features of allergy, such as hives, or they may be typical in most babies, such as colic. CMA may involve one or more organs, such as the skin and digestive system.2
System | Symptoms |
|---|---|
Digestive (tummy-related) | Diarrhoea Constipation Vomiting Reflux Blood and/or mucus in stools Abdominal discomfort Excessive wind |
Skin
| Eczema (persistent) Rashes or itching (persistent) Hives Swelling of eyes, throat, lips & face |
Airways (breathing-related)
| Sneezing Runny or blocked nose (nasal congestion) Difficulty breathing Wheeze (whistling noise) Cough (persistent) |
General
| Irritability (persistent) Refusal of feeds Poor weight gain |
Immediate vs delayed reactions
Symptoms of CMA can present as:
1. Immediate: onset within minutes or up to 2 hours
This type of CMA is formally known as IgE-mediated, where the immune system produces an antibody called immunoglobulin E in response to a trigger (in the case of CMA, the proteins in cow’s milk). It is usually diagnosed through allergy testing (blood or skin tests), along with an allergy-focused review.1
Symptoms can be mild e.g., redness of the skin or hives. Anaphylaxis is the term used for severe, life-threatening and rapid allergic reactions (within minutes) involving the airways, breathing and circulatory systems, e.g. difficulty breathing, limp or unresponsive.1
2. Delayed: onset within 2-48 hours
This type of CMA is formally known as non-IgE-mediated, involving a different immune response (one that does not produce immunoglobulin E). It cannot be tested in the same way as IgE-mediated CMA and relies on an allergy-focused review, followed by a period of cow’s milk removal and reintroduction.1
Whilst these symptoms are usually mild and common in many babies (e.g., colic or constipation), they can overlap with other conditions and can be misdiagnosed. This is why it’s important to seek advice early.2,3
What to do next
If CMA in your baby is suspected, especially if symptoms worsen or recur, seek an allergy-focused review with your GP.3
Keep a record of feeding patterns, symptoms and timings to share. Often, a referral to the right healthcare professional (HCP) can support diagnosis and management of CMA. Dietary changes should only be made under the guidance of a HCP.
When to seek urgent medical attention
Severe symptoms of an allergic reaction (anaphylaxis) require urgent medical attention (dial 999).
Do not reintroduce cow’s milk and seek an allergy-focused review with a GP. Severe symptoms include:3
- difficulty or noisy breathing
- wheezing (whistling) or persistent cough
- hoarse cry
- swollen tongue
- difficulty swallowing
- change in skin tone (pale)
- becoming suddenly sleepy or floppy
- collapse or unconsciousness
Nutricia’s support for families
Nutricia offers a range of additional resources that you may find helpful. These can be accessed via the Nutricia website, where you'll find dedicated sections providing further practical information and support. If you'd like any additional guidance, the Nutricia Resource Centre team is always happy to help on 03457 623653.
More information can be found on the Allergy UK website, which has a dedicated section for parents on the identification, diagnosis and management of CMA.
Frequently asked questions
Yes, although it’s very rare in exclusively breastfed/chestfed babies (and anaphylaxis is even rarer). Reassuringly, most parents can continue to breastfeed/chestfeed. Breastmilk (human milk) remains the best source of nutrition for baby and provides health benefits for both the baby and the parent producing the milk.3 Alternative formulas suitable for CMA are available where breastfeeding/chestfeeding is not possible, or if removing cow’s milk from the mother/feeding parent’s diet does not improve symptoms
No. CMA is an immune system-driven response, whereas lactose intolerance is due to a lack of lactase (the enzyme needed to digest lactose). Symptoms of lactose intolerance are commonly digestive-related (e.g., bloating, pain and loose stools), and is rare in babies and young children. Most babies with CMA do not need to avoid lactose.4
Yes. Dairy refers to all mammalian milks such as cows, goats and sheep, which share similar proteins such as whey and casein. For this reason, babies with CMA should avoid all forms of dairy from all mammals sources, as they will likely experience an allergic reaction if used.4
It may take up to 4 weeks for symptoms of CMA to resolve when sources of cow’s milk have been removed from the diet. The response may be faster in those with IgE-mediated (immediate) CMA. A trial elimination of 2–4 weeks is usually recommended.2
Most children (80-90%) will fully outgrow their CMA by school age.5
Outgrowth of CMA is usually a gradual, stepwise process under the guidance of a HCP. Most young children can eventually reintroduce cow’s milk, starting with baked and cooked forms. This may be at home or at an allergy clinic, depending on the severity of their symptoms.4
Written by Kiran Atwal
Kiran is a registered dietitian with over a decade of clinical expertise and research experience. Her career history spans across many NHS Trusts and industry, focusing on the management of complex conditions including food allergies. Kiran serves as Co-chair of the British Dietetic Association Paediatric Specialist Group committee, and regularly authors work in clinical textbooks, magazines, scientific conferences and journals.
- Fiocchi, et al. World Allergy Organ J. 2022;15(1):100609.
- Meyer, et al. World Allergy Organ J. 2023;16(7):100785.
- Fox, et al. Clin Transl Allergy. 2019;9:40.
- Meyer R and Venter C. In: Shaw V (ed). Clinical Paediatric Dietetics. 5th ed. London: Wiley, 2020. pp.315–38.
- Skripak, et al. J Allergy Clin Immunol. 2007;120(5):1172–7.