Milk allergy symptoms, which differ from person to person, occur a few minutes to a few hours after you or your child drinks milk or eats milk products.

Immediate signs and symptoms of milk allergy might include:

• Hives

• Wheezing

• Itching or tingling feeling around the lips or mouth

• Swelling of the lips, tongue or throat

• Coughing or shortness of breath

• Vomiting

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

• Loose stools or diarrhea, which may contain blood

• Abdominal cramps

• Runny nose

• Watery eyes

• Colic, in babies

Milk allergy or milk intolerance?

A true milk allergy differs from milk protein intolerance and lactose intolerance. Unlike milk allergy, intolerance doesn't involve the immune system. Milk intolerance requires different treatment from 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 narrows the airways and can 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 milk allergy, so you can avoid future and potentially worse reactions.

Anaphylaxis is a medical emergency and requires treatment with an epinephrine (adrenaline) shot (EpiPen, Adrenaclick, others) and a trip to the emergency room. Signs and symptoms start soon after milk consumption 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

All true food allergies are caused by an immune system malfunction. If you have milk allergy, 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 to 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 within minutes.

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

Certain factors may increase the risk of developing milk allergy:

• Other allergies. Many children allergic to milk also have other allergies. Milk allergy may develop before other allergies.

• Atopic dermatitis. Children who have atopic dermatitis — a common, chronic inflammation of the skin — are much more likely to develop a food allergy.

• Family history. A person's risk of a food allergy increases if one or both parents have a food allergy or another type of allergy or allergic disease — such as hay fever, asthma, hives or eczema.

• Age. Milk allergy is more common in children. As they age, their digestive systems mature, and their bodies are less likely to react to milk.

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

• Allergies to other foods — such as eggs, soy, peanuts or even beef

• Hay fever — a common reaction to pet dander, dust mites, grass pollen and other substances