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How is a Milk Allergy Diagnosed and What Does it Mean?

cartoon with dairy products and cartoon man with upset stomach

Milk allergy most often occurs in young children, but people of all ages can develop this condition. Indeed, milk is one of the most common food allergens, and it is estimated that 1 in 5 American kids have this food allergy. Notably, one-third of children with milk allergies have severe reactions. 

Please continue reading to learn more about allergies to cow's milk, including what it is, how it is diagnosed and treated, and whether it is the same as lactose intolerance.

What is a milk allergy?

Milk allergy is a common type of food allergy in children. It occurs because of an abnormal immune system response to milk and milk products. The most common culprit is cow's milk, but other types of milk (from animals such as goats, sheep, and buffalos) can also cause an allergic reaction.

Milk allergies can occur in babies who are breastfed as well as those given powdered milk or formula. Some children outgrow their milk allergy by the time they are 3-5 years of age, while others never outgrow it and need to avoid milk and milk products throughout life. 

Why does milk allergy occur?

All food allergies, including milk allergies, are caused by a malfunction of the immune system. In people who have a milk allergy, the immune system mistakes milk proteins as harmful and responds by forming immunoglobulin E (IgE) antibodies to neutralize the allergen (milk protein). When a person with a milk allergy consumes dairy products, the IgE antibodies tell the immune system to release histamine and other chemicals, which causes allergic symptoms.

What are the signs and symptoms of a milk allergy?

Milk allergy symptoms can be mild or severe. Consuming milk can cause anaphylaxis, a severe and potentially life-threatening allergic reaction for some people with milk allergies.

The allergic reaction typically occurs within hours of consuming milk. Symptoms can include hives, itching, swelling, wheezing, coughing, drop in blood pressure, vomiting, diarrhea, abdominal cramping, colic in babies, watery eyes, and runny nose.

How do doctors diagnose milk allergy?

You may have a milk allergy diagnosed based on your medical history, symptoms, and family history. Your doctor may recommend you have allergy tests administered. This can include allergy skin tests (patch tests or puncture tests) or oral food challenge tests for detecting milk allergy. A blood test for immunoglobulin E (IgE) antibodies may also be done to confirm milk allergy. It requires an allergy specialist to interpret allergy skin tests correctly.

How is a food allergy to milk protein different from lactose intolerance?

Lactose intolerance is a condition that affects up to 1 in 3 Americans. It is more common in adults and does not involve the immune system. Rather, it occurs due to an inability to tolerate foods that contain lactose, a sugar found in dairy products. People who are lactose intolerant cannot digest lactose and experience bloating, gas, and diarrhea after drinking milk or eating dairy products. 

What to avoid if you have a cow's milk allergy?

Food allergy research has shown that the only way to prevent milk allergy is to avoid the foods that cause allergic reactions. If you are allergic to milk, there are two types of milk protein you need to avoid:

  • Casein: present in the solid curds of curdled milk
  • Whey: present in the liquid part of curdled milk

You can be allergic to one or both milk proteins. To avoid allergic reactions, you need to eliminate milk and milk products from your diet. A true milk-free diet can be challenging because milk proteins are present in other dairy products besides milk, such as yogurt, butterfat, vegetable oil, ice cream, gelato, cheese, cottage cheese, cream cheese, sour cream, etc. It can also be present in processed foods. Most people who are allergic to cow's milk commonly also have reactions to buffalo, sheep, and goat's milk. Allergic reactions to non-dairy milk like soy milk and rice milk are less common.

If you suffer from milk allergic disorders, read food labels carefully and check with the server or chef before ordering meals in restaurants (ask about ingredients and how the food is cooked). Look for whey, casein, and ingredients with the prefix “lact.” You should know that non-dairy milk products like processed food, processed meats, baked goods, candies, artificial cheese or artificial butter flavor, hydrolysates, and protein powders can contain milk protein.

What is the best medicine for milk allergy?

There is no medicine that can prevent an allergic reaction. The only way to prevent a serious allergic reaction is to avoid milk and milk products. 

However, if you or your child accidentally consumes milk and has a mild allergic reaction, an antihistamine (allergy medication) may help to reduce allergic symptoms. 

If you have a history of a severe allergy to milk or your child is at risk of severe reactions from milk, ask your doctor about carrying an emergency epinephrine pen. If your child drinks milk and has a severe allergic reaction like anaphylaxis, you may need to use this device (EpiPen, Adrenaclick). Also, ask your doctor about wearing a medical alert bracelet/necklace that mentions your food allergy.

While a mild reaction can typically be treated at home, a severe reaction may require you to seek emergency medical care in the emergency room immediately. 

Is there a pill for dairy allergy?

As mentioned above, there is no pill to prevent dairy allergy. Antihistamines can be used to treat a mild reaction. EpiPen (epinephrine injection) or treatment in the ER may be required for a severe reaction if someone who is allergic to milk consumes cow’s milk or other dairy products. 

Unlike food allergies, for which there is no pill, there is a pill that can treat lactose intolerance. Lactase enzyme tablets or drops (Lactaid) are available over-the-counter. Taking the tablets before a meal or adding drops to milk can help people who do not tolerate milk digest it better. However, these pills don't work for everyone.


  1. https://www.mayoclinic.org/diseases-conditions/milk-allergy/symptoms-causes/syc-20375101
  2. https://pubmed.ncbi.nlm.nih.gov/23622009/
  3. https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance/definition-facts#