What is milk allergy?
A milk allergy is an immune reaction to one of the many proteins in animal milk. It’s most often caused by the alpha S1-casein protein in cow’s 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.
A milk allergy is sometimes confused with lactose intolerance because they often share symptoms. The two conditions are very different, however. Lactose intolerance occurs when a person lacks the enzyme (lactase) to metabolize lactose — a milk sugar — in the intestines.
How common is milk allergy?
Cow’s milk is the leading cause of allergic reactions in young children and one of eight foods that are responsible for 90 percent of childhood allergies. Please discuss with your doctor for further information.
What are the symptoms of milk allergy?
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:
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?
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.
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
- Shock, with a marked drop in blood pressure
There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.
When should I see my doctor?
If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.
What causes milk allergy?
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.
What increases my risk for milk allergy?
There are many risk factors for milk allergy, such as:
- Other allergies. Many children allergic to milk also have other allergies. Milk allergy is often the first to develop.
- 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 — such as hay fever, asthma, hives or eczema.
- Milk allergy is more common in children. As they age, their digestive system matures, and their bodies are less likely to react to milk.
Diagnosis & treatment
The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.
How is milk allergy diagnosed?
At your appointment, your allergist will take a detailed history, including asking what you ate, what symptoms you experienced, how long the symptoms lasted and what you did to alleviate them. The most common allergy tests are a skin-prick test or a blood test; both look for the presence of immunoglobulin E (IgE) antibodies, which develop when your body is exposed to a substance to which it is sensitive. These antibodies trigger the release of chemicals that cause allergic symptoms.
In the skin-prick test, a liquid containing milk or a milk protein extract is placed on your forearm or back. Your skin is pricked with a small, sterile probe, allowing the liquid to seep into your skin. If you develop a raised, reddish welt, typically within 15 to 20 minutes, that can indicate an allergy. In a blood test, a blood sample is tested for the presence of IgE antibodies. The results are reported as a numerical value.
Research suggests that some types of milk proteins (casein and two proteins found in whey, alpha-lactalbumin and beta-lactalbumin) are more likely to cause serious reactions. A newer type of blood test, known as a component test, can help the allergist determine your risk for a serious reaction by looking for allergies to those specific proteins.
Another test your allergist may order is an oral food challenge. Under medical supervision, you’ll eat small amounts of a substance containing milk or a milk powder to see if a reaction develops. Because of the possibility that a reaction could be severe, this test is conducted in your allergist’s office or at a food challenge center with emergency equipment and medication on hand.
How is milk allergy treated?
The only way to prevent an allergic reaction is to avoid milk and milk proteins. This can be difficult because milk is a common ingredient in many foods. Also, some people with a milk allergy can tolerate milk in some forms, such as milk that’s heated in baked goods, or some processed foods, such as yogurt. Talk to your doctor about what to avoid.
Despite your best efforts, if you or your child accidentally consumes milk, medications such as antihistamines may reduce mild signs and symptoms of an allergic reaction. Taken after exposure to milk, an antihistamine may help relieve discomfort.
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 EpiPen, Auvi-Q, others) at all times. Have your doctor or pharmacist demonstrate how to use this device so that you’re prepared for an emergency.
Lifestyle changes & home remedies
What are some lifestyle changes or home remedies that can help me manage milk allergy?
The following lifestyles and home remedies might help you cope with milk allergy:
Having a serious allergy or being the parent of a child with a potentially life-threatening allergy can be stressful. Talking to others in similar situations can be helpful. Besides offering support and encouragement, they may also provide useful coping tips, such as how to deal effectively with school officials to ensure your child’s medical needs are met. Ask your doctor if there are any support groups in your area, or contact the Asthma and Allergy Foundation of America.
If you have any questions, please consult with your doctor to better understand the best solution for you.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Review Date: November 22, 2017 | Last Modified: December 9, 2019
Milk allergy. https://www.mayoclinic.org/diseases-conditions/milk-allergy/basics/definition/con-20032147. Accessed November 22, 2017.
Milk Allergies (Milk Protein Allergy). https://www.healthline.com/health/allergies/milk#overview1. Accessed November 22, 2017.
Milk & Dairy Allergy. http://acaai.org/allergies/types-allergies/food-allergy/types-food-allergy/milk-dairy-allergy. Accessed November 22, 2017.