Milk allergy is an abnormal response by the body’s immune system to milk and products containing milk. Cow’s milk is the usual cause of milk allergy, but milk from sheep, goats and buffalo also can cause a reaction. Some children who are allergic to cow’s milk are allergic to soy milk, too. Milk allergy is one of the most common food allergies in children.
A milk allergy 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. Rarely, 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 by age 3.
Milk allergy symptoms, which differ from person to person, occur a few minutes to a few hours after drinking milk or eating milk products.
Signs and symptoms that may take more time to develop include:
- Loose stools, which may contain blood
- Abdominal cramps
- Coughing or wheezing
- Runny nose
- Watery eyes
- Itchy skin rash, often around the mouth
- Colic, in babies
Milk 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 from 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 or products containing milk.
Rarely, milk allergy can cause anaphylaxis, a life-threatening reaction that can narrow the airways and block breathing. If you or your child has a reaction to milk, tell your doctor about it no matter how mild the reaction was. Tests can help confirm a milk allergy, so you can take steps to 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
- Shock, with a marked drop in blood pressure
Tests When food is the cause of an allergic reaction, it isn’t always easy to pinpoint what food is to blame. To evaluate whether you or your child has a milk allergy, your doctor may:
- Ask detailed questions about signs and symptoms
- Perform a physical exam
- Have you keep a detailed diary of the foods you or your child eats
- Have you eliminate milk from your diet or your child’s diet (elimination diet) — and then have you add back the food to see if it causes a reaction
He or she may also recommend one or both of the following tests:
- Skin test. In this test, your skin is pricked and exposed to small amounts of the proteins found in milk. If you’re allergic, you develop a raised bump (hive) at the test location on your skin. Allergy specialists usually are best equipped to perform and interpret allergy skin tests. Be aware that this type of test isn’t always accurate for detecting a milk allergy.
- Blood test. A blood test can measure your immune system’s response to milk by measuring the amount of certain antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to milk. However, this test isn’t always accurate in correctly identifying a milk allergy.
If your examination and test results can’t confirm a milk allergy, your doctor might administer an oral challenge, in which you are fed different foods that may or may not contain milk in increasing amounts to see if you react to the ones that contain milk.
If your doctor suspects your symptoms are caused by something other than a food allergy, you may need other tests to identify — or rule out — other medical problems.
The only way to prevent an allergic reaction is to avoid milk and milk proteins altogether. This can be difficult because milk is a common ingredient in many foods.
Despite your best efforts, you or your child may still come into contact with milk. If this happens, medications, such as antihistamines, may reduce signs and symptoms of a mild milk allergic reaction. These drugs can be taken after exposure to milk to control an allergic reaction and help relieve discomfort. Talk with your doctor about which medications might work best for you.
If you or your child has a serious allergic reaction (anaphylaxis), you may need an emergency injection of epinephrine (adrenaline) and a trip to the emergency room. If you’re at risk of having a severe reaction, you or your child may need to carry injectable epinephrine (such as an EpiPen) at all times. Have your doctor or pharmacist demonstrate how to use this device so you’re prepared for an emergency.
Allergy shots, also sometimes called immunotherapy, haven’t been proved effective for treating food allergies, but research is ongoing.