Scottsdale, Arizona - Milk allergy, one of the most common food allergies in children, is an abnormal response by the body's immune system to milk and products containing milk. Cow's milk is the usual cause, but milk from sheep, goats, buffalo and other mammals also can cause a reaction.

An allergic reaction usually occurs minutes to hours after consuming milk. Signs and symptoms of milk allergy range from mild to severe and can include wheezing, vomiting, hives and digestive problems. Sometimes, milk allergy can cause anaphylaxis - a severe, life-threatening reaction.

Avoidance is the primary treatment for milk allergy. Fortunately, most children outgrow a milk allergy. Those who don't outgrow it may need to continue to avoid milk products.

Milk allergy symptoms, which differ from person to person, occur a few minutes to a few hours after drinking milk or eating milk products.

Immediately after consuming milk, signs and symptoms of a milk allergy might include:

  • Hives
  • Wheezing
  • Vomiting

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

  • Loose stools, which may contain blood
  • Diarrhea
  • Abdominal cramps
  • Coughing or wheezing
  • Runny nose
  • Watery eyes
  • Itchy skin rash, often around the mouth
  • Colic, in babies

Milk allergy or milk intolerance?

A true milk allergy differs 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 from a true milk allergy.

Common signs and symptoms of milk protein intolerance or lactose intolerance include digestive problems, such as bloating, gas or diarrhea, after consuming milk or products containing milk.

Anaphylaxis

Milk allergy can cause anaphylaxis, a life-threatening reaction that can narrow the airways and block breathing. Milk is the third most common food, after peanuts and tree nuts, to cause anaphylaxis.

If you or your child has a reaction to milk, tell your doctor, no matter how mild the reaction. Tests can help confirm a milk allergy, so you can avoid future and potentially worse reactions.

Anaphylaxis is a medical emergency and requires treatment with an epinephrine (adrenaline) shot and a trip to the emergency room. Signs and symptoms start soon after consuming milk and can include:

  • Constriction of airways, including a swollen throat that makes it difficult to breathe
  • Facial flushing
  • Itching
  • Shock, with a marked drop in blood pressure

When to see doctor

See your doctor or an allergist if you or your child experiences milk allergy symptoms shortly after consuming milk. If possible, see your doctor during the allergic reaction to help the doctor make a diagnosis. Seek emergency treatment if you or your child develops signs or symptoms of anaphylaxis.

All true food allergies are caused by an immune system malfunction. Your immune system identifies certain milk proteins as harmful, triggering the production of immunoglobulin E (IgE) antibodies to neutralize the protein (allergen). The next time you come in contact with these proteins, IgE antibodies recognize them and signal your immune system to release histamine and other chemicals, causing a range of allergic signs and symptoms.

There are two main proteins in cow's milk that can cause an allergic reaction:

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

You or your child may be allergic to only one milk protein or both. These proteins may be hard to avoid because they're also in some processed foods. And, most people who react to cow's milk will react to sheep's, goat's and buffalo's milk. Less commonly, people allergic to cow's milk are also allergic to soy milk.

Food protein-induced enterocolitis syndrome (FPIES)

A food allergen can also cause what's sometimes called a delayed food allergy. Although any food can be a trigger, milk is one of the most common. The reaction, commonly vomiting and diarrhea, usually occurs within hours after eating the trigger rather than minutes.

Unlike some food allergies, FPIES usually resolves over time. As with typical milk allergies, preventing an FPIES reaction involves avoiding milk and milk products.