Milk allergy is one of the most common food allergies in children. Milk allergy is an abnormal response by the body’s immune system to milk and products that contain milk. An allergic reaction occurs soon after consuming milk. 

Causes 

If you have milk allergy, the immune system identifies milk proteins as harmful, triggering the production of immunoglobulin E (IgE) or antibodies that neutralize protein. There are two main proteins that can cause an allergic reaction: Casein, which is found in the solid part (curd) of milk that curdles and whey, found in the liquid part of milk that remains after milk curdles.

Milk Allergy Symptoms

• Hives 
• Upset stomach
• Vomiting
• Coughing or shortness of breath
• Swelling of the lips, tongue, or throat
• Itching or tingling feeling around the lips or mouth
• Anaphylaxis (rare)

Other signs and symptoms that may take more time to develop:

• Loose stools or diarrhea
• Runny nose
• Watery eyes
• Colic in babies

Milk Allergy vs. Milk Intolerance

Unlike milk allergy, intolerance does not involve the immune system. Milk intolerance requires different treatment from true milk allergy. The common signs of milk protein intolerance or lactose intolerance include bloating, gas or diarrhea, after consuming milk products. 

When to See a Doctor

See your doctor or specifically, an allergist if you or your child experiences any of the signs mentioned above after consuming milk. Seek immediate medical attention if you or your child develops signs or symptoms of anaphylaxis, such as constriction of airways, swollen throat, facial flushing, itching, shock, with a marked drop in blood pressure.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

Food allergen can also caused a delayed food allergy. Although any food can be a trigger, milk is one of the most common. The reactions are commonly vomiting and diarrhea. However, unlike milk allergies, FPIES usually resolves over time. 

Risk Factors

The following may increase the chances of developing milk allergy:

• Other allergies
• Atopic dermatitis
• Family history
• Age

Complications

Children who are allergic to milk are also more likely to develop other health problems including allergies to egg, soy, peanuts or even beef, and hay fever, or a common reaction to pet dander, dust mites, grass, pollen, and other substances.