Milk Allergy

Milk allergy is one of the most common food allergies, especially in young children. It happens when your body’s immune system mistakenly treats milk proteins as harmful invaders, triggering reactions that can range from mild discomfort to life-threatening emergencies.

Table of contents

• What is milk allergy?
• Who is affected by milk allergy?
• The difference between milk allergy and lactose intolerance
• Symptoms of milk allergy
• What causes milk allergy?
• How is milk allergy diagnosed?
• Treatment and management
• Foods and ingredients to avoid
• Outgrowing milk allergy

What is milk allergy?

Milk allergy is an abnormal response by your body’s immune system (your body’s defense system) to milk and products containing milk. When you have a milk allergy, your immune system treats proteins found in milk as dangerous substances and tries to fight them off^[1].

Cow’s milk is the most common cause of milk allergy, but milk from other animals such as sheep, goats, and buffalo can also trigger reactions. If you are allergic to cow’s milk, there is a high likelihood that you will also react to milk from these other animals^[2].

The proteins in milk that cause allergic reactions fall into two main groups: casein and whey proteins. Casein is the protein that remains when milk spoils and curdles. Whey proteins include alpha-lactalbumin and beta-lactoglobulin. Most people with milk allergy are sensitive to both casein and whey proteins^[4].

Who is affected by milk allergy?

Milk allergy can affect anyone at any age, but it is most common in infants and young children. The condition typically appears within the first few months of life, usually before six months of age^[4].

Approximately 2% to 3% of children in the United States have a milk allergy^[2][3]. In the developed world, the prevalence appears to be 2 to 3% in infants under one year old^[4]. Milk allergy can develop in both formula-fed and breastfed babies^[2].

While milk allergy is one of the most common food allergies in children, it is also among the most common food allergies in adults, though it affects far fewer adults than children^[3].

The difference between milk allergy and lactose intolerance

A true milk allergy is very different from lactose intolerance, and it’s important not to confuse the two conditions. They require different treatments^[1].

Milk allergy involves your immune system. When you have a milk allergy, your body creates special antibodies called immunoglobulin E (IgE) after your first exposure to milk. These antibodies bind to cells in your skin, airways, and blood vessels. When they encounter milk proteins again, they release histamine and other chemicals that cause allergic symptoms^[2].

Lactose intolerance, on the other hand, does not involve the immune system at all. It occurs when your body cannot properly digest lactose (the sugar found in milk) because you don’t produce enough of an enzyme called lactase. This leads to digestive problems such as bloating, gas, and diarrhea, but it is not life-threatening and does not cause the broader range of symptoms seen in milk allergy^[1][7].

There is also a condition called milk protein intolerance in infants, which is different from both milk allergy and lactose intolerance. This causes digestive symptoms but does not involve IgE antibodies^[2].

Symptoms of milk allergy

An allergic reaction to milk usually happens soon after you or your child consumes milk or milk products. Symptoms can start within a few minutes to a few hours after eating or drinking milk^[1]. The severity of symptoms can vary greatly from person to person^[2].

There are two main types of milk allergy reactions. IgE-mediated reactions happen quickly, usually within minutes to up to two hours after consuming milk. Non-IgE mediated reactions are slower and may take from two hours up to 72 hours to develop^[7].

Immediate symptoms of milk allergy may include:

• Hives (raised, red, itchy bumps on the skin)
• Wheezing (a whistling sound when breathing)
• Itching or tingling feeling around the lips or mouth
• Swelling of the lips, tongue, or throat
• Coughing or shortness of breath
• Vomiting
• Nausea
• Abdominal pain or cramps
• Diarrhea
• Rash

These are based on information from multiple sources^[1][2][6].

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

These are mentioned in source^[1].

Milk allergy can cause anaphylaxis, a severe, life-threatening reaction. Anaphylaxis can cause difficulty breathing, chest tightness, wheezing, dizziness, a drop in blood pressure, and loss of consciousness. Without immediate treatment with epinephrine (adrenaline), anaphylaxis can result in death^[1][2][8].

What causes milk allergy?

If you have a milk allergy, the proteins in milk cause your immune system to overreact. Your body mistakenly identifies these proteins as harmful invaders and launches an immune response to fight them off^[2].

Milk contains more than 20 different protein fractions. The major allergens belong to two groups: casein proteins (alpha-s1, alpha-s2, beta, and kappa-casein) and whey proteins (alpha-lactalbumin and beta-lactoglobulin)^[4].

Healthcare providers and medical researchers are not exactly sure why some people suddenly develop a milk allergy. The sudden development of milk allergy in adults can happen but is very rare^[2][7].

How is milk allergy diagnosed?

Diagnosing milk allergy can be challenging because symptoms vary widely and can be similar to other conditions. It is important to see a doctor or an allergist (a specialist trained in allergies) for proper diagnosis^[8].

To diagnose a milk allergy, your healthcare professional will:

• Ask detailed questions about your symptoms and what you ate
• Perform a physical examination
• Have you keep a detailed food diary
• Have you eliminate milk from your diet and then add it back to see if it causes a reaction

One or more of the following tests may be recommended^[9]:

Skin test: In this test, your skin is pricked and exposed to small amounts of milk proteins. If you have an allergy, a raised bump called a hive forms at the test location. Allergy specialists are usually best equipped to perform and interpret these tests. Keep in mind that this test is not completely accurate for detecting milk allergy^[9].

Blood test: A blood test measures your immune system’s response to milk by measuring the amount of IgE antibodies in your blood. However, this test is also not completely accurate in identifying milk allergy^[9].

A newer type of blood test, known as a component test, can help determine your risk for a serious reaction by looking for allergies to specific milk proteins such as casein, alpha-lactalbumin, and beta-lactalbumin, which are more likely to cause serious reactions^[6].

Oral food challenge: If examination and test results cannot confirm milk allergy, your healthcare professional might give you an oral challenge. In this test, 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. Because of the possibility of a severe reaction, this test is conducted in your allergist’s office or at a food challenge center with emergency equipment and medication on hand^[9].

The only reliable way to diagnose milk allergy with certainty is through a double-blind, placebo-controlled challenge (DBPCFC), where neither you nor the doctor knows whether you are receiving milk or a substitute during the test^[11].

Treatment and management

At present, there is no cure for milk allergy. The only proven treatment is to completely avoid milk and all milk-containing products^[1][9][11].

Avoiding milk and milk products is the primary way to manage milk allergy. This can be difficult because milk is a common ingredient in many foods. You must carefully read food labels on everything you buy, as food companies can change ingredients at any time^[9].

Exclusion and reintroduction of milk and other dairy foods should only be done under strict medical supervision, particularly in cases of anaphylaxis. If long-term exclusion is required, you need alternative sources of calcium and protein to ensure adequate nutrition and growth, especially for children. Do not change your child’s diet without consulting a doctor, or your child could suffer from nutritional deficiencies^[8].

If you have a severe milk allergy that can cause anaphylaxis, your doctor will prescribe an adrenaline injector (such as EpiPen or Anapen). You should carry this with you at all times. If you have a severe allergic reaction, call emergency services immediately and use your adrenaline injector right away. The person having the reaction should not stand or walk. Further doses of adrenaline may be given if there is no response after 5 minutes^[8].

Your doctor will give you an action plan for anaphylaxis that explains exactly what to do in an emergency^[8].

Some children with milk allergy can tolerate baked milk. Approximately 70% of children with cow milk allergy can eat baked milk products without reacting. Baked milk is milk that has been extensively heated, which changes the structure of the proteins that cause allergy. Young children who can eat baked milk without reacting may be more likely to outgrow their milk allergy at an earlier age than those who react to baked milk. However, you should never try giving baked milk products without guidance from your doctor^[3].

Foods and ingredients to avoid

If you have a milk allergy, you must avoid all dairy products. These include:

• Milk (including buttermilk, powdered milk, evaporated milk, condensed milk, skim milk, whole milk, low-fat milk, and nonfat milk)
• Butter and butter fat
• Cheese, including cottage cheese
• Cream, including sour cream and whipped cream
• Yogurt
• Ice cream
• Custard and pudding

Milk proteins may also be present in many other foods. Always check labels carefully. Processed meats, including hot dogs, sausages, and lunch meats frequently contain milk or are processed on milk-containing equipment^[5].

Foods that often contain milk proteins include:

• Baked goods (bread, cookies, crackers, cakes, donuts)
• Chocolate and cream candies
• Creamed or scalloped foods and white sauces
• Mashed potatoes
• Salad dressings
• Many Indian foods (which use ghee, a form of butter)
• Chewing gum
• Granola bars

These are mentioned across several sources^[5][6].

When reading labels, you must avoid products that list these ingredients:

• Casein, caseinates (ammonium, calcium, magnesium, potassium, sodium)
• Whey, whey protein, whey products
• Curds
• Lactalbumin, lactalbumin phosphate
• Lactoglobulin
• Milk protein, milk derivative, milk solids
• Hydrolysates (casein, milk protein, protein, whey, whey protein)
• Ghee
• Nougat
• Rennet casein
• Artificial butter flavor

These are compiled from sources^[5].

Products labeled as “non-dairy” are not necessarily safe for people with milk allergy. These products do not contain butter, cream, or milk, but they may still use other milk-containing ingredients. You must check the ingredient list carefully^[5].

Importantly, the following ingredients are safe and do not contain milk protein: lactic acid and lactose in medications^[5].

Milk proteins can also be found in cosmetics, creams, ointments, and some medications. Always check labels on these products as well^[9].

Outgrowing milk allergy

Fortunately, most children outgrow milk allergy. Many children with milk allergy will outgrow it before they reach school age, around 5 years old. By the age of 6, the prevalence has fallen to less than 1%^[4].

However, experts once believed that the vast majority of children would outgrow milk allergy by the time they turned 3, but recent studies contradict this. In one study, fewer than 20% of children had outgrown their allergy by age 4. Still, about 80% of children are likely to outgrow their milk allergy before they are 16^[6][11].

In a small number of people who do not outgrow their allergy to milk, it will persist into adulthood. Where this happens, people are more likely to experience more severe allergic reactions. In some adults with mild IgE-mediated milk allergy, a period of prolonged and strict avoidance may result in the allergy becoming more severe^[7].

Those who don’t outgrow milk allergy may need to continue to avoid milk products throughout their lives^[1].