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Paediatrics

Cow's Milk Protein Allergy

Cow's milk protein allergy is an immune-mediated reaction to milk proteins in infancy, either immediate and IgE-mediated or delayed and non-IgE-mediated; diagnosis depends on an allergy-focused history and, for non-IgE disease, a supported elimination and reintroduction plan.

In a nutshell

Cow's milk protein allergy is an immune reaction in infancy. Immediate IgE-mediated reactions occur rapidly and may cause urticaria, vomiting, wheeze or anaphylaxis; delayed non-IgE-mediated disease causes gastrointestinal or skin symptoms over hours to days. Diagnose from an allergy-focused history: use targeted IgE testing for suspected immediate allergy and a time-limited elimination/reintroduction pathway for suspected non-IgE disease. Protect nutrition with dietetic support and an appropriate hypoallergenic formula or maternal exclusion plan.

Classic presentation

A formula-fed infant has reproducible urticaria and vomiting soon after milk, or a breastfed infant has delayed blood-streaked stools, eczema and poor growth that improve with supported cow's-milk-protein exclusion.

Key points

  • Milk protein allergy is immune-mediated; lactose intolerance is not and does not cause anaphylaxis.
  • IgE-mediated reactions are rapid; non-IgE-mediated reactions are delayed and have no single diagnostic blood test.
  • Use an allergy-focused history before testing; avoid broad panels and unvalidated tests.
  • For non-IgE disease, use a limited elimination trial followed by planned reintroduction with dietetic support.
  • Extensively hydrolysed formula is suitable for most formula-fed infants; amino-acid formula is considered for severe disease, anaphylaxis, faltering growth or non-response.
  • Treat anaphylaxis immediately with IM adrenaline and do not attempt home reintroduction after an immediate systemic reaction without specialist direction.

First-line investigation

Allergy-focused history and examination; targeted skin-prick or specific-IgE testing for suspected IgE-mediated disease, or supported elimination and reintroduction for non-IgE disease.

Management

Treat severe reactions

  • Give IM adrenaline immediately for airway, breathing or circulation compromise after milk exposure and follow the current RCUK emergency algorithm.7,6,8

Establish the phenotype

  • Take an allergy-focused history before testing and distinguish immediate IgE-mediated, delayed non-IgE-mediated and non-allergic symptoms.1,2
  • Use targeted IgE testing only when immediate allergy is suspected; do not use broad panels, IgG tests or other unvalidated tests.1,3

Exclude safely

  • Use a limited elimination and planned reintroduction for suspected non-IgE disease, with dietetic advice and growth monitoring.1,4
  • Use an appropriate prescribed hypoallergenic formula for formula-fed infants; extensively hydrolysed formula suits most, with amino-acid formula for selected severe or non-responsive cases.1,3,5,9

Review tolerance and risk

  • Refer severe, systemic, growth-compromising, multiple-allergy or diagnostically uncertain cases and plan reintroduction safely; do not reintroduce at home after immediate systemic reactions without specialist advice.1,6,3

Exam traps

  • A positive IgE test shows sensitisation, not necessarily clinical allergy.
  • Partially hydrolysed or lactose-free formula does not treat cow's milk protein allergy.
  • Do not diagnose non-IgE allergy from reflux or colic alone without a supported elimination and reintroduction response.
  • Dietary restriction without dietetic support can cause nutritional harm.
  • Home reintroduction is unsafe after an immediate systemic reaction unless the specialist plan says otherwise.

Illustrations

Cutaneous reaction to milk protein exposureClinical photograph showing a localised erythematous rash after exposure to a product containing casein, illustrating a possible cutaneous manifestation of cow's milk protein allergy; retain source attribution while image-quality remediation remains separate.Wikiuserwheatallergy, Wikimedia Commons · CC0

Key sources

  1. NICE CG116, Food allergy in under 19s: assessment and diagnosis (NICE guideline published 23 February 2011 and last reviewed 21 September 2018; current recommendations cover allergy-focused history, targeted testing, elimination/reintroduction, dietetic advice and referral)Published 23 Feb 2011 | Updated 21 Sept 2018
  2. NHS, Food allergies in babies and young children (NHS information on symptoms, delayed presentations and specialist formula discussion)
  3. BSACI, guideline for the diagnosis and management of cow's milk allergy (UK specialist allergy guideline; current BSACI page and guideline resource checked)Published 1 Aug 2014
  4. NICE QS118, Food allergy quality standard (Quality statement on elimination and reintroduction for suspected non-IgE-mediated food allergy)Published 26 Feb 2014
  5. NHS, Types of formula milk (NHS information stating that partially hydrolysed formula is not suitable for cow's milk allergy and that diagnosed allergy needs an appropriate hypoallergenic formula)
  6. NICE NG258, Anaphylaxis: assessment and referral after emergency treatment (Current NICE anaphylaxis pathway for observation, discharge planning and specialist allergy referral)Published 27 May 2026 | Updated 4 Jun 2026
  7. Resuscitation Council UK, Emergency treatment of anaphylaxis (UK emergency treatment guideline, current RCUK algorithm for immediate IM adrenaline and refractory escalation)Published 1 May 2021
  8. BNF for Children, current allergy and anaphylaxis prescribing information (UK paediatric prescribing source; use current product monographs and local emergency protocols for medicines and doses)
  9. BNF for Children, current specialist infant formula prescribing information (UK paediatric prescribing source; product choice and quantities should follow current BNF and local dietetic or prescribing guidance)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.