Milk allergyThe immune system attacks milk proteins. Expect hives, eczema, congestion, wheezing or stomach upset, sometimes within minutes.
Lactose intoleranceThe gut lacks lactase, the enzyme that digests milk sugar. Gas, cramps and diarrhea an hour or two later. No skin or breathing symptoms.
The overlapBoth cause stomach pain. If dairy also gives you a rash, a stuffy nose or a cough, think allergy and test.
Allergy Reacts To Protein · Intolerance To Sugar