Cow milk intolerance, cow milk allergy.

1. Big picture

Cow milk-related symptoms in infancy are common, but the key exam skill is to separate:

1. Cow milk protein allergy = immune reaction to cow milk proteins.
2. Cow milk intolerance / lactose intolerance = non-immune digestive problem, usually due to lactase deficiency.
3. Physiological infant problems that are often wrongly blamed on milk: colic, regurgitation, functional constipation, normal stool variation.

The exam-winning sentence:

Cow milk protein allergy is the most common food allergy in infancy; it may present with eczema, vomiting/reflux-like symptoms, chronic diarrhea, constipation, poor weight gain, or blood in stool, and diagnosis is based on symptom improvement after cow milk elimination and recurrence after challenge.

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2. Definitions