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Cows Milk Protein Allergy

What is it?

Cows’ milk protein allergy (CMPA) is the most common food allergy in infants and children – affecting around 2-7% in the UK.

CMPA usually develops in early infancy, following the first exposure to cows’ milk, either through the use of formula milk or weaning foods. In some instances it can occur in breastfed infants due to maternal milk intake although incidence of this is much rarer at 0.5% (Host 1994).

CMPA occurs as the result of an adverse, immunological response by the body to one of the proteins found in cow’s milk. It can be separated into three types; IgE mediated (sometimes called a ‘classic allergy’), non-IgE mediated, or mixed. ‘IgE’ refers to a specific type of immunoglobulin (antibody) which is sometimes produced and can be used to identify which type of allergy it is.

Symptoms vary between individuals depending on the immune response.

IgE mediated allergies tend to produce symptoms within minutes of food consumption and can affect the whole body including the respiratory tract, producing symptoms such as vomiting, reflux, wheezing, coughing, eye/lip swelling, runny nose and anaphylaxis (life-threatening whole body reaction). Non-IgE mediated allergy tends to have a more delayed response, sometimes up to 48 hours after consumption, and produce symptoms which predominantly affect the skin and digestive tract such as dermatitis, skin urticaria (hives), diarrhoea, stomach pain and constipation.

Seeing these symptoms in young infants can be distressing for parents and therefore it is important that a diagnosis is quickly sought to prevent further anxiety and rule out other conditions.

CMPA is usually diagnosed by a GP with knowledge of allergies, or by a paediatric allergist, depending on the availability of specialist centres. A diagnosis is usually made based on a combination of the following:

•    If IgE-mediated allergy is suspected: A clinical diet and family history, IgE blood testing, skin prick test.

•    If a mixed allergy is suspected: A clinical diet and family history, IgE blood testing, skin prick test, elimination diet.

•    No IgE-mediated allergy: A clinical diet and family history, elimination diet, re-challenge.

The path to an official diagnosis can be slow and frustrating for parents; however it is the only way to truly establish what is causing the symptoms. It may be tempting for parents to try and ‘self-diagnose’ or visit ‘alternative’ allergy testing practitioners – but these can have dangerous and misleading results.

Appropriate management of CMPA is important to ensure adequate infant nutrition and growth during their early years. CMPA is managed by avoidance of all cows’ milk containing products combined with use of an alternative cow’s milk free formula to ensure healthy growth,

If CMPA is diagnosed when the infant is still being exclusively breastfed then breastfeeding should continue with the mother avoiding cows’ milk protein, to ensure none passes through. Breastfeeding should ideally continue for at least 6 months – once a mother decides to stop breastfeeding she should consult her health visitor or doctor for advice on a suitable formula for her baby.  

If CMPA is diagnosed in a mixed-fed or bottle-fed infant then a suitable hypoallergenic formula should be prescribed. In the case of an IgE mediated allergy this should be made immediately to prevent anaphylaxis; in non-IgE mediated allergy this can be tapered with babies’ usual milk over a period of days to get accustomed to the taste.

During weaning, foods with cows’ milk should also be avoided such as cheese and yoghurts – and ingredients lists should be checked thoroughly. Names which indicate that cows’ milk is in a product include: milk solids, cream, yoghurt, cheese/cheese powder, casein, buttermilk, butter, whey powder, lactose etc. A dietitian can supply a full list of ingredients to check. All HiPP products list milk as a product in a bright yellow ‘Contains’ box below the ingredients listing.

Nearly 90% of infants with CMPA will grow out of this allergy by three years of age  (Venter et al 2008) – so parents should be reassured that for the majority of infants this will not be permanent. A doctor will advise on when to ‘re-challenge’ with cows’ milk – to determine tolerance and prevent prolonged avoidance.  

Host, A. (1994) Cow’s milk protein allergy and intolerance in infancy; some clinical, epidemiological and immunological aspects, Pediatric Allergy and Immunology, Vol 5, Issue 6, pages 5-36.

Novembre, E., Vierucci, A. (2001) Milk/allergy intolerance and atopic dermatitis in infancy and childhood, Allergy, Vol 56 pages 105-108.

Venter, C., Pereira, B, Voigt, K, et al (2008) Prevalence and cumulative incidence of food hypersensitivity in the first 3 years of life, Allergy, Vol 63 (3) pages 354-359.