Between 6 and 12 months of age, it's recommended to introduce foods derived from cow's milk, such as yogurt and cheese as part of the early phases of solid food introduction. At a child's first birthday, cow's milk can be introduced as they start to transition from breast milk or formula to help ensure they get the important nutrients needed to support growth and development. Whether it's milk, yogurt, cheese or another dairy food, these first tastes are when a milk allergy becomes apparent.

However, the difference between a milk allergy and lactose intolerance can be confusing. Here's a look at the two, how they're treated and why it's important to know the difference.

What is a milk allergy?

A milk allergy occurs when the body's immune system mistakenly identifies the protein in milk and other dairy products as something the body should fight off. In the United States, about 2% to 3% of infants have an allergy to cow's milk. Most children outgrow a milk allergy by age 3. There are different types of milk allergy. One type is caused by immunoglobulin E (IgE) antibodies and can be distinguished by immediate, life-threatening symptoms. Another type is caused by non-IgE antibodies and has symptoms that occur more gradually and sometimes with less severe symptoms.

Symptoms of milk allergy caused by IgE antibodies usually appear within two hours after the child has milk. These symptoms can be life-threatening and cause signs of anaphylaxis. Anaphylaxis happens quickly with symptoms that include:

• Difficulty breathing, wheezing, or gagging.
• Facial swelling.
• Hives.
• Bluish skin color.
• Loss of consciousness.
• Vomiting.

If your child has these symptoms, don't hesitate: Call 911 or your local emergency number. After emergency treatment, work with a healthcare professional — ideally an allergist — to determine what caused the reaction and to figure out how to avoid another. You'll also want to establish a plan of action with your healthcare team, should it happen again. This often involves being prescribed an emergency epinephrine autoinjector (EpiPen).

Milk allergy symptoms caused by non-IgE antibodies typically present more than two hours after exposure. Your child might be irritable or fussy, with symptoms such as:

• Vomiting.
• Loose stools, possibly containing blood.
• Hives or skin rashes.
• Refusing to eat.
• Excessive crying.
• Digestive problems.

Cow's milk is the usual cause of milk allergy; however, milk from sheep, goats and water buffalo also can cause a reaction. And some children who are allergic to cow's milk are allergic to soy milk too.

Because most infant formula is derived from cow's milk, infants who are formula-fed may have a higher risk of developing a milk allergic reaction than those who are breastfed. Researchers don't fully understand why some infants develop a milk allergy and others don't. Your child's healthcare team can give you guidance. If you use formula and your child has a milk allergy, your doctor may advise you to switch to another type of formula that's less likely to cause an allergic reaction.

What is lactose intolerance?

Lactose intolerance is when the body can't fully digest and absorb lactose, which is the natural sugar in milk. This is because the body needs the enzyme lactase (with an A) to break down lactose (with an O).

Up to 70% of the world's population have difficulty digesting lactose, called lactose non-persistence. It's most common in people with Asian or Native American heritage where nearly 100% of adults cannot tolerate lactose. More than half of people with Hispanic, Black or Ashkenazi Jewish heritage cannot tolerate lactose. Rates are lowest for people with Northern European heritage where only about 2% don't have the lactase necessary to break down lactose.

Signs of lactose intolerance usually start out subtle but may increase with age. Common signs include abdominal pain, gas and diarrhea. Lactose intolerance can be assessed by eliminating lactose from the diet and watching for improvement. It also can be detected with a breath test.

Why is the distinction important?

Confusing a milk allergy and lactose intolerance can lead to making unnecessary diet changes. People with milk allergies should not consume milk, cheese, or yogurt since it could cause a serious and life-threatening reaction. If your child has a milk allergy, it can be helpful to work with a dietitian in addition to an allergist who can teach you how to spot milk products in ingredients lists.

In contrast, people with lactose intolerance can likely consume some dairy. They just have to be careful about it to find the amounts that work for them without causing discomfort.

Some people find that they can have a cup of milk or a scoop of ice cream without feeling symptoms. Some dairy foods also are lower in lactose than others. For example, 1 cup of whole milk has 12.8 grams of lactose while an ounce of Swiss cheese has 0.02 grams.

Children with lactose intolerance might be able to have a small amount, such as 4 to 8 ounces of milk, spaced throughout the day. They might also tolerate dairy when they have it with other foods. Yogurt tends to be better tolerated than milk because the healthy bacteria in yogurt partially digests the lactose.

People who can't tolerate lactose can take lactase supplements or choose dairy products that contain added lactase to help with digestion. Lactose-free milks are also available. These options allow people to get the vitamins and minerals found in dairy without experiencing the side effects that they get with lactose.

Keep in mind that a surprising number of nondairy products may contain milk. While the amount of lactose may be insignificant for people with lactose intolerance, the exposure to milk protein is problematic for people with cow's milk allergy. A few products are listed below:

• Bread or other baked goods.
• Breakfast cereals.
• Baking or pancake mixes.
• Dehydrated potatoes or soup mixes.
• Margarine.
• Sauces such as salad dressings.
• Chocolate, caramel and butterscotch.

What to eat if your child can’t have dairy

If your kids can't have dairy, consider working with a dietitian to identify foods that can fill in those gaps:

• Calcium: Kale, tofu, fortified soy beverage.
• Vitamin D: fortified cereals, fortified soy beverage, salmon.
• Iodine: cod, iodized salt, eggs.
• Vitamin B12: beef, turkey, eggs.

Finding safe ways to consume dairy can help with a child's nutrient status. Dairy foods such as milk, cheese and yogurt are an important contributor of protein, calcium and vitamin D, which are essential for bone health and overall growth and development.

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April 02, 2025