Milk Allergy Symptoms: Could You Be Allergic to Milk?

Cow’s milk allergy is the most common food allergy among infants and children. It’s estimated that 80% of children will outgrow the allergy by the time they turn 16 years old.

Treatment for milk allergy typically involves avoiding all cow’s milk and products made with cow’s milk. A cow's milk allergy might also be called a dairy allergy or milk protein allergy.

This article explains possible milk allergy symptoms, plus everything you need to know to tell if your symptoms are caused by a milk allergy or lactose intolerance (which is a different condition).

Person's hand taking a jug of milk from a supermarket cooler
Grace Cary / Getty Images.

How Do You Know You Have a Milk Allergy?

You may notice you or your child has an allergy to milk if symptoms develop after consuming cow’s milk or something made with cow’s milk or dairy. Symptoms typically occur within minutes to two hours after consuming the milk or dairy product.

Someone allergic to cow’s milk might also have an allergy to milk from other animals, such as goat or sheep's milk.

In infants, milk allergy symptoms may appear days to weeks after they first receive a cow’s milk-based formula or after drinking breast milk from a person who has consumed dairy products.

People of any age may have a milk allergy, though it is less common to develop one as an adult. Milk allergies are more frequently seen in young children and infants, with an estimated 2–3% of children younger than 3 years old having one.

The good news is that most children outgrow their milk allergy, with around 80% no longer having a milk allergy by the time they are 16 years old.

Milk Allergy Symptoms

Symptoms of a cow’s milk or dairy allergy can range from mild to severe. Someone with a milk allergy may react differently than someone else with a milk allergy. In addition, an individual may react differently to separate instances of exposure to dairy products.

Milk allergy symptoms can include:

Milk Allergy vs. Lactose Intolerance Symptoms

Though a milk allergy and lactose intolerance are sometimes confused with one another, they are not the same thing. A milk allergy is an immune system reaction to one or more proteins in a milk or dairy product and can have severe or life-threatening consequences. 

Lactose intolerance means someone cannot properly digest lactose, the sugar in milk. This is because they lack the enzyme (a substance that helps bring about a specific chemical reaction) lactase, which breaks lactose in the body down. Lactose intolerance also differs from a milk allergy in that it typically appears in older children (over the age of 5) or adults.

Symptoms of lactose intolerance are usually uncomfortable and may be similar to those of a milk allergy. However, they are not life-threatening. 

Lactose intolerance symptoms typically include:

  • Bloating
  • Diarrhea
  • Gas
  • Abdominal pain
  • Nausea
  • Vomiting
  • Stomach growling or rumbling sounds

What Causes a Milk Allergy?

A milk allergy occurs when your body's immune system reacts to certain proteins in milk. The two main proteins in milk are casein and whey. Casein makes up about 80% of milk proteins and is found in the “solid” part of milk. Whey is found in the liquid part of milk and makes up about 20% of milk proteins.

Some people are allergic to only casein, some are allergic to only whey, and others are allergic to both.

Milk allergy can take two forms. When a milk or dairy product is consumed, the body may overreact and create immunoglobulin E (IgE) antibodies to “fight off” the milk proteins. This allergic reaction releases chemicals, such as histamine, that are responsible for allergy symptoms.

Or, the allergy may be non-IgE mediated. In these cases, other immune cells may react to the milk protein, primarily producing symptoms in the gastrointestinal tract.

Food Protein-Induced Enterocolitis Syndrome (FPIES)


Food protein-induced enterocolitis syndrome (FPIES) is a type of non-IgE-mediated food allergy that primarily occurs in infants. Any food can trigger FPIES, though cow’s milk is one of the most common triggers. Other common food triggers include soy and some grains, such as rice, barley, and oats.

Symptoms are usually delayed for several hours (two to four hours) after consuming the triggering food and include:

  • Severe vomiting
  • Diarrhea
  • Dehydration
  • Weight loss
  • Fatigue
  • Failure to thrive in infants or children

Though it is rare, new-onset FPIES has been reported in adults. In these rare instances, an adult may suddenly develop a milk allergy.

Risk Factors for Milk Allergies

You may be more likely to develop an allergy to milk if you have certain risk factors, such as:

  • Family history: Allergies are often hereditary. One study reported that infants with a family history of allergy were three times more likely to develop a cow’s milk allergy compared to those without a family history.
  • Other allergies: Individuals with one allergy are more likely to have other allergies.
    A milk allergy may develop before or after other allergies have been identified.
  • Atopic dermatitis: Children with atopic dermatitis (a common, chronic inflammatory skin disease) are more likely to have a cow’s milk allergy. Between 33% and 63% of children with eczema (atopic dermatitis is a type of eczema) also have food allergies. One study reported over 70% of kids with a cow’s milk allergy also had atopic dermatitis.
  • Age: Milk allergies are more commonly diagnosed in infants and young children. The majority of children outgrow their milk allergy as they get older and their digestive system matures.

Complications Related to Milk Allergies

Kids with a milk allergy may also experience other problems, such as:

  • Nutritional deficiencies: Children who eliminate milk and dairy products from their diet may not get enough of some nutrients in their diet, such as calcium and vitamin D. Additionally, some children may experience slowed growth patterns due to food restrictions, feeding, and other dietary challenges.
  • Decreased quality of life: Many common and surprising foods contain milk, milk products, or milk proteins, making food choices tricky sometimes. Avoiding all foods and beverages you or your child is allergic to may lead to stress or anxiety, especially if it is a severe allergy. Not being able to have milk (or foods that contain it) at family or social gatherings can also impact quality of life.

How Can I Prevent Reactions?

The best way to prevent a reaction is to avoid all milk and milk products. 

Milk is one of the eight major allergens in the United States and must be listed on all packaged foods, making it easier to identify if milk is in a product. This is required by federal law, either in a “contains” statement on the package or within the ingredient list itself.

Common dairy products and foods with milk include:

  • All milk (fat-free, low-fat, reduced-fat, whole, buttermilk, condensed, evaporated)
  • Cream (heavy, light, sour, whipping, whipped, creamer) and half-and-half
  • Yogurt
  • Pudding and custard
  • All cheese, cottage cheese, and cheese flavoring
  • Butter and ghee
  • Ice cream, frozen yogurt, gelato
  • Candies, such as milk chocolate, nougat, caramel
  • Protein powders or shakes
  • Cream-based soups, sauces, and roux

Sometimes, it isn’t obvious that a product contains milk. This is why it’s important to carefully read food labels and examine ingredients lists. Even if a food is labeled "milk-free," “dairy-free,” or "non-dairy," it may still contain milk proteins. If you are unsure, contact the manufacturer to verify whether a product contains milk or milk ingredients.

Other milk ingredients to look out for include:

  • Casein, caseinates
  • Rennet casein
  • Curds
  • Whey (all forms)
  • Hydrolysates (casein, milk protein, protein, whey, whey protein)
  • Lactalbumin, lactalbumin phosphate, lactoglobulin, lactoferrin
  • Lactose, lactulose
  • Milk derivative, milk powder, milk protein, milk solids, nonfat milk solids, nonfat dry milk

When dining out or eating foods prepared by someone else, it’s important to ask how the food was prepared. For example, some protein foods, such as shrimp or steak, and vegetables may be cooked or sauteed with butter, while other foods may have had milk added before or after cooking.

Milk in Baked Goods

Some people with a milk allergy may tolerate foods containing milk that has been extensively heated. For example, they may be able to eat milk that is baked in cakes, muffins, breads, cookies, or crackers. Children who are allergic to fresh milk and dairy products but can tolerate baked milk may be more likely to outgrow their milk allergy at an earlier age than those who have a reaction to baked milk. Consult an allergist before adding any foods with baked milk to the diet. They can help you determine whether you should completely avoid milk and other dairy products or if a trial of baked milk should be considered.

Milk Alternatives for Babies, Infants, and Toddlers

Feeding your infant with a milk allergy may be trickier to navigate; however, there are more dairy-free and hypoallergenic options today than ever before.

Human Milk

Human milk is the recommended exclusive source of nutrition for babies for the first six months of life, along with continued breastfeeding/chestfeeding after solid foods are introduced for two years of life or beyond.

Typically, lactating people are advised to eliminate milk and dairy products from their diet if their baby has a cow’s milk protein allergy. However, research suggests this may not be necessary.

A 2020 study estimated that for more than 99% of infants with proven cow’s milk allergies, the breast milk of a person consuming cow’s milk does not contain enough milk allergen to trigger an allergic reaction.

Consult with your baby’s pediatrician or allergist to determine whether you should eliminate dairy from your diet while nursing a baby who has a cow’s milk protein allergy.

Hypoallergenic Formula

This specialized formula type is extensively processed and broken down, making it less likely to cause an allergic reaction.

Some hypoallergenic (or elemental) formulas are extensively hydrolyzed but still milk based, while others are amino acid based—but both reduce the risk of an allergic reaction. Your infant’s pediatrician can help you decide which formula is best for your baby.

Soy-Based Formula

Soy-based formulas are based on soy protein instead of milk and are sometimes used as an alternative to milk-based formulas. Talk to your child's healthcare provider about whether they recommended them.

The American Academy of Pediatrics notes that soy-based formulas may be given to infants with cow's milk allergies after 6 months of age if the soy formula doesn't produce gastrointestinal symptoms. Some children with a cow's milk protein allergy may also be reactive to soy protein.

Cow’s Milk Alternative Beverages

For toddlers over 1 year old, there are many options for replacing milk in their diet. These include rice, almond, cashew, oat, pea, hemp, and coconut milk.

The nutritional composition of these milk alternatives varies widely, so be sure to read the food label to ensure it is not loaded with unnecessary ingredients, such as added sugars and oils. 

When to Seek Emergency Care

If you or your child is experiencing a severe allergic reaction, seek medical attention immediately.

Signs and symptoms of an anaphylactic reaction may include:

  • A red rash with hives or welts that is usually itchy
  • Swelling of the throat or other areas of the body
  • Wheezing
  • Passing out
  • Chest tightness
  • Trouble breathing
  • Coughing
  • Hoarse voice
  • Difficulty swallowing
  • Vomiting
  • Diarrhea
  • Abdominal cramping
  • Pale or red color to the face and body
  • A feeling of impending doom

If you or your child has an allergy to milk, it is important to keep an epinephrine injection device with you at all times because this is the first-line treatment for anaphylaxis reactions.

Summary

A cow’s milk allergy is when your body’s immune system reacts to the proteins in milk, creating antibodies that trigger an allergic reaction. The two main milk proteins are casein and whey. Milk allergy is commonly seen in infants and young children, though people of any age can have an allergy to milk.

Many children outgrow their milk allergy as they age. Milk allergy symptoms typically occur within minutes to hours after consuming milk and may include swelling, hives, trouble breathing, vomiting, diarrhea, tightness of the throat, coughing, wheezing, upset stomach, or anaphylaxis.

Lactose intolerance is different from a milk allergy in that it doesn’t involve the immune system but is instead caused by the gut's inability to properly break down lactose, the type of sugar found in milk.

Food protein-induced enterocolitis syndrome (FPIES) is another type of food allergy, of which milk is a common trigger. FPIES symptoms usually occur hours after eating the offending food or beverage.

Risk factors for milk allergy include a family history of allergy, having other allergies or atopic dermatitis, and being young of age. Avoiding all milk and dairy products is the best way to prevent an allergic reaction from occurring.

Infants with cow’s milk allergy may breastfeed or have a hypoallergenic formula. Toddlers and children may substitute milk with a cow’s milk alternative beverage, such as rice, nut (e.g., almond, cashew), pea, hemp, oat, or coconut milk. Soy milk or formula is not typically recommended in children with a cow’s milk allergy due to possible reactivity to soy proteins.

Seek emergency medical attention if you or your child is experiencing a severe allergic reaction or showing signs of anaphylaxis. Always consult with a healthcare provider or allergy specialist before making any changes to your or your child’s diet or treatment plan.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Brittany Poulson, MDA, RDN, CD, CDCES
Brittany Poulson, MDA, RDN, CDCES, is a registered dietitian and certified diabetes care and education specialist.