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Dr. Andrew Rynne
Dr. Andrew Rynne

Family Physician

Exp 50 years

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Article Home Children's Health Cow's milk allergy

Cow's milk allergy

Cow's milk is one of the most common allergy-causing foods in children, and it's the leading cause of allergic reactions in very young children. Allergic reactions usually occur a few minutes to a few hours after you consume milk.

Signs and symptoms of milk allergy differ from person to person and occur within a few minutes to a few hours after ingesting milk. In some cases, reactions to a milk allergy develop after exposure to milk for an extended period of time. Rarely, infants have an allergic reaction to small amounts of cow's milk protein passed through their mother's breast milk.

Signs of a milk allergy that may occur immediately after consuming milk include:

  • Wheezing
  • Vomiting
  • Hives

Signs and symptoms that may take more time to develop include:

  • Loose stools (which may contain blood or mucus).
  • Diarrhea.
  • Abdominal cramps.
  • Coughing or wheezing.
  • Runny nose.
  • Skin rash.

TMilk allergy or milk intolerance ?

It's important to differentiate a true milk allergy from milk protein intolerance or lactose intolerance. Unlike a milk allergy, intolerance doesn't involve the immune system. Milk intolerance causes different symptoms and requires different treatment than does a true milk allergy. Common signs and symptoms of milk protein or lactose intolerance include digestive problems, such as bloating, gas or diarrhea, after consuming milk.

There are two types of protein in milk that can cause an allergic reaction:

  • Casein, which is found in the solid part (curd) of milk that curdles.
  • Whey, which is found in the liquid part of milk that remains after milk curdles.


Seek emergency treatment if you develop any signs or symptoms of anaphylaxis, such as:

  • Constriction of airways that makes it difficult to breathe.

  • Shock, with a severe drop in blood pressure.
  • Rapid pulse.
  • Dizziness or lightheadedness.

Children who are allergic to milk are much more likely to develop certain other health problems, including:

  • Allergies to other foods — such as eggs, soy or peanuts.
  • Hay fever — a reaction to pet dander, dust mites, grass pollen and other substances.
  • Gastro esophageal reflux disease (GERD), a type of heartburn in which stomach acid or bile flows back (refluxes) into the esophagus.


  • Avoidance of milk.
  • Hypoallergenic formulas are produced by using enzymes to break down (hydrolyze) milk proteins, such as casein or whey.
  • Soy-based formulas are based on soy protein instead of milk. Soy formulas are fortified to be nutritionally complete — but, unfortunately, many children with a milk allergy develop an allergy to soy.