When suspecting CMA, an allergy focused history can be helpful to establish whether allergy testing such as skin prick testing or specific blood tests might be appropriate. These tests are only useful where there is a history of a rapid onset reaction occurring within 2 hours of exposure to cow’s milk. For more delayed reactions (2-72 hours after), a period of cow’s milk elimination for around 2-4 weeks followed by gradual home reintroduction is advised to confirm or rule out CMA.6 There are many other tests marketed to diagnose food allergies and intolerances, but these are often not evidence-based and may lead to unnecessary dietary restrictions.
Cow’s Milk Allergy (CMA) or Lactose Intolerance?
Understanding the difference: CMA vs Lactose Intolerance
The conditions CMA and lactose intolerance are often confused as both conditions can cause discomfort after consuming cow’s milk containing products. Each condition has a different underlying cause and requires different treatment to resolve the presenting symptoms.
Cow's Milk Allergy (CMA) is an immune system response to one or more of the proteins found in cow’s milk (casein and whey). Lactose intolerance does not involve the immune system, it is a digestive issue caused by a deficiency of the enzyme lactase, which is needed to break down lactose, the sugar present in milk.
Comparison table
| CMA | Lactose Intolerance |
|---|---|---|
Cause | An immune reaction to milk protein(s) | A deficiency of the lactase enzyme |
Trigger | The proteins in milk (casein and/or whey) | Lactose, the naturally occurring sugar in milk |
Symptoms | Gastrointestinal (tummy-related) Diarrhoea or constipation Vomiting or reflux Blood and/or mucus in stools Abdominal discomfort or excessive wind Skin Eczema (persistent) Rashes or itching (persistent) Hives Swelling of the lips, eyes, face or throat Respiratory (breathing-related) Wheeze Cough (persistent) Breathing difficulties Rhinitis (sneezing, runny or blocked nose) or nasal congestion General Persistent Irritability or colic Food refusal or aversions Poor weight gain (or faltering growth in more severe cases) | Solely gastrointestinal symptoms including bloating, diarrhoea and flatulence (gas) |
Onset | Within minutes up to 2 hours for immediate onset (IgE-mediated) CMA or 2-72 hours for delayed onset (non-IgE-mediated) CMA | Typically, within a few hours of consuming lactose |
Age group | Most common in infants and young children | More common in older children and adults |
Management | Elimination of cow’s milk | A lactose-free diet or lactase supplements |
What is Cow’s Milk Allergy (CMA)?
Signs and symptoms of CMA
CMA is an adverse reaction to one or more of the proteins present in milk. The immune system mistakenly recognises milk protein as a harmful substance, triggering an allergic response. CMA is usually the first allergy to develop and most commonly presents in early life, with onset rarely occurring after 12 months of age.1
There are 2 different types of CMA: IgE mediated (immediate onset) and non-IgE mediated (delayed onset). Sometimes there may be mixed CMA where some symptoms show quickly and others present later. Symptoms can affect more than one body system and can include skin symptoms, gastrointestinal (gut) symptoms, respiratory symptoms and anaphylaxis in rare cases. Please see table above for more detail on typical symptoms.
CMA can occur in exclusively breastfed/chestfed babies if dairy is included in the mother’s/feeding parent’s diet. However, this is rare, affecting around 0.5% of exclusively breastfed/chestfed infants.2
What is Lactose Intolerance?
Signs and symptoms of lactose intolerance
Lactose intolerance is not an allergy. It occurs when the body cannot break down the sugar present in milk (lactose) due to the body not producing enough of the enzyme lactase. Lactase is needed to break lactose into smaller sugars which helps it to be more easily digested and absorbed. When it is not broken down it travels through the gut and is fermented by bacteria which can cause unpleasant symptoms including diarrhoea, bloating, and flatulence (gas).
Persistent (primary) lactose intolerance is rare in early childhood and most often presents after 5 years of age,3 due to decreasing levels of lactase production. It can however be more common, with earlier onset in some ethnic groups.4
Lactose intolerance can sometimes occur as a temporary condition (secondary lactose intolerance) following a gastrointestinal infection (tummy bug). In most cases this will usually resolve within 6-8 weeks. It is also sometimes seen in premature babies where they haven’t yet started producing enough lactase enzyme and improves as the gut matures.5
Diagnosing CMA vs Lactose Intolerance: What to Expect?
If you suspect CMA or lactose intolerance it’s not advisable to self-diagnose or eliminate dairy without seeking the advice of a suitably qualified healthcare professional. This is especially important for infants and children, as over-restricting their diet may compromise their growth and development.
Diagnosing CMA
Diagnosing Lactose Intolerance
Exploring symptom history and keeping a food diary to look for patterns can be helpful in establishing whether lactose may be problematic. A period of lactose avoidance followed by reintroduction can help to confirm a lactose intolerance. Hydrogen breath testing may be used to diagnose lactose intolerance, although this is not always widely available.
Managing each condition for parents and carers
Managing CMA
Strict avoidance of all cow’s milk products is recommended to treat CMA. Lactose-free products typically still contain milk protein and will not be suitable. Milk from other mammals such as goat’s and sheep’s milk contain similar proteins to cow’s milk and are generally not well tolerated in CMA.7
If symptoms occur with maternal/parental intake of dairy when breastfeeding/chestfeeding, elimination of cow’s milk in the feeding parents diet is advised. A parent producing breastmilk (human milk) is advised to take calcium and vitamin D supplements.2 If formula feeding, a suitable hypoallergenic formula can be prescribed.
Support from a healthcare professional, such as a registered dietitian, can help ensure both breastfeeding mums'/feeding parent and child remain well-nourished when following a cow’s milk-free diet.
They can also advise how and when to reintroduce cow’s milk again as CMA is not usually a lifelong condition.
In the case of severe allergy an emergency plan is important to ensure appropriate treatment is given without delay in the event of a serious allergic reaction. This can be discussed with your healthcare professional.
Managing Lactose Intolerance
Lactose containing foods (including milk, soft cheese, ice-cream etc) may need to be limited or avoided. Some individuals experiencing lactose intolerance may be able to tolerate small amounts of lactose and can have lactose free dairy products where the lactase enzyme has already been added to break down the lactose. Some dairy products such as hard cheeses are naturally low in lactose and may be tolerated. Lactose free formula milk and lactase enzyme supplements are also available to purchase if needed. Breastfeeding/chestfeeding can continue without dietary lactose restriction, as the lactose content of breastmilk (human milk) is not influenced by the feeding parent's lactose intake.
There is no risk of severe allergic reaction with this condition.
Can you have both CMA and Lactose Intolerance?
It is rare, but not impossible to experience both CMA and lactose intolerance at the same time. This can sometimes be a temporary issue following a gut infection or if initial presentation of CMA is severe. If CMA is persistent into later childhood where lactose intolerance becomes more common the conditions may coexist.2 Support from a registered dietitian is recommended to ensure safe dietary management.
Nutricia’s support for families
Nutricia has a range of additional resources that may be helpful for you. You can explore these on the Nutricia website, where you’ll find dedicated sections with further practical information and support. If you’d like more guidance, the Nutricia Resource Centre team are always happy to help: 03457 623653.
Several UK organisations provide independent education, research, and support for allergy management:
www.allergyuk.org/wp-content/uploads/2022/03/Lactose-Intolerance.pdf
When to seek professional help
Please contact your healthcare provider if:
- Your child has ongoing symptoms following consumption of dairy
- There are concerns surrounding poor growth, persistent diarrhoea or feeding difficulties
- There are signs of a severe allergic reaction (anaphylaxis) which include breathing difficulties, swelling and collapse
Author details:
Zoe is a Specialist Paediatric Dietitian leading an NHS Cow’s Milk Allergy Service in the South-West. Zoe holds a BSc (Hons) in Dietetics, a Postgraduate Certificate in Advanced Professional Practice in Paediatric Dietetics and has undertaken the Cow’s Milk Protein Allergy course provided by The British Dietetic Association.
- Luyt, et al. Clin Exp Allergy. 2014;44(5):642-72.
- Vandenplas, et al. J Pediatr Gastroenterol Nutr. 2024;78(2):386-413.
- Heine, et al. World Allergy Organ J. 2017;10(1):41.
- Heyman, Pediatrics. 2006;118(3):1279-1286.
- Bhatnagar, et al. BMJ. 2007;334(7608):1331-2.
- Meyer, et al. World Allergy Organ J. 2023;16(7):100785.
- Lajnaf, et al. Food Chem Toxicol. 2023;178:113929.