GP FAQ Cow’s Milk Protein Allergy

Although the numbers diagnosed with cow’s milk protein allergy (CMPA) have increased, it is important to remember that it affects less than 2% of infants.

There are some key questions to ask when cow’s milk protein allergy is suspected including family history of atopy, sources of cow’s milk protein and how much is being ingested, presenting symptoms with the sequence of clinical presentation of each symptom, feeding or growth concerns, previous management and any previous changes in diet and their effect.

More detailed information can be found on Allergy UK’s website through the following link:

Most infants with CMPA develop symptoms before 1 month age and often within 1 week after introduction of CMP- based formula.

CMPA can cause both acute IgE-mediated reactions (within 2 hours) e.g. urticarial rash, wheeze, vomiting and delayed reactions, that may be either non IgE-mediated or mixed (> 2 hours) e.g. mild-moderate eczema, gastro-oesophageal reflux.

Severe CMPA hypersensitivity symptoms may include anaphylaxis, severe eczema or faltering growth.

Remission of symptoms is expected in 45 – 50% of infants at 1 year, 60 -75% at 2 years and 85 – 90% at 3 years.

During and after a viral gastrointestinal infection the gut is very sensitive and drinking milk and dairy can cause a transient cow’s milk protein allergy or lactose intolerance.

Investigation and management:

Skin-prick test does not provide a definitive diagnosis of allergy – history may be more important.

Milk allergy in primary care (MAP) guidelines give a clear pathway for the investigation and management of CMPA which is different for bottle fed and breastfeeding babies. Please follow the link to the pathway:

  • A child should be referred to a paediatric dietician when CMPA is suspected and/or when cow’s milk protein is excluded from the diet
  • If breast feeding, breast milk remains the ideal choice for the CMPA infant
    • A maternal dairy exclusion diet should be initiated
  • For infants who are not breast fed, an appropriate hypoallergenic formula is required.These formulae vary in palatability and should therefore be introduced as soon as possible. If possible, there should be a transition to the introduction with an incremental mixing of the milks
  • Tolerance of cow’s milk protein can develop after 6 months of exclusion diet and is likely to develop to baked milk products first


This is a simple guide to infant formulas:

Allergy UK:  guidance for re-introduction of milk protein


Lozinsky AC, Meyer R, Anagnostou K, et al. (2015) Cow’s milk protein allergy from diagnosis to management: a very different journey for general practitioners and parents. Children 2(3):317–329.