Many people have an allergy to milk. As yogurt is a fermented milk product, a person who feels unwell after eating it may have a milk allergy or an intolerance to lactose.

Milk allergy is among the most common food allergies in young children. A yogurt allergy is essentially a dairy allergy because the production of this food involves fermenting milk with a yogurt culture.

However, in some cases, lactose intolerance may cause symptoms following dairy consumption.

Anyone who experiences food-related symptoms should speak with their doctor to determine the next steps.

This article explores yogurt and milk allergies and lactose intolerance, covering causes, symptoms, treatment options, and risks.

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An allergy to cow’s milk and milk products is a prevalent food allergy in babies and young children, occurring in about 2.5% of children under 3 years of age. Although people usually outgrow a milk allergy, it can sometimes persist into adulthood.

If a child is allergic to fresh milk but can tolerate baked milk without an allergic reaction, they are more likely to outgrow the allergy earlier.

On the other hand, if a child has high levels of antibodies against cow’s milk, the allergy is more likely to continue. A doctor can use a blood test to measure these antibodies and predict whether the child could outgrow the milk allergy. An allergist can also perform an in-office oral challenge to help determine whether the child has outgrown the allergy.

A milk allergy is the body’s response to a protein in milk. When someone with a milk allergy consumes milk, the liquid’s proteins bind with immunoglobulin E (IgE) antibodies from their immune system. The immune defenses see this as a threat, leading to the symptoms of the allergic reaction.

Unexpected sources

Many people with a cow’s milk allergy do not tolerate milk from other animals, such as sheep and goats. In addition, milk proteins might be present in unexpected products, such as:

  • canned tuna fish
  • sausage
  • deli meats
  • chewing gum
  • bodybuilding and energy drinks

Under the Food Allergen Labeling and Consumer Protection Act of 2004, if a product contains milk or milk proteins, the label must include this information. However, the law does not extend to products that may contain traces of milk because their production takes place in a facility that also processes milk products.

People with a milk allergy should, therefore, exercise caution in trying new foods that could trigger an allergic reaction.

Learn more about milk substitutes here.

Symptoms

The symptoms of a milk allergy can range from mild to severe, and they can sometimes even be life threatening. They usually occur within 2 hours of consuming milk and include:

Cow’s milk can potentially cause a severe reaction called anaphylaxis, the symptoms of which can occur suddenly and progress quickly. The symptoms may include:

Any child or adult experiencing these symptoms should seek immediate medical attention.

Treatment

The best approach to managing a milk allergy is to avoid items containing milk. These products include:

  • animal milk
  • yogurt
  • cheese
  • butter
  • ice cream

If an individual has mild milk allergy symptoms, the doctor may suggest using an antihistamine, such as diphenhydramine (Benadryl) or cetirizine hydrochloride (Zyrtec).

A severe milk allergy that leads to anaphylaxis will require immediate treatment with epinephrine. The doctor will advise the individual to keep an epinephrine auto-injector with them at all times to treat themselves should they experience anaphylaxis in the future.

In March 2020, the Food and Drug Administration (FDA) released a safety alert to warn the public that epinephrine auto-injectors (EpiPen, EpiPen Jr., and generic forms) may malfunction. This could prevent a person from receiving potentially lifesaving treatment during an emergency. If a person has a prescription for an epinephrine auto-injector, they can view the recommendations from the manufacturer here and talk with their healthcare provider about safe usage.

Lactose intolerance is different than a milk allergy. A milk allergy involves an immune reaction to milk proteins. In contrast, in people with lactose intolerance, the small intestine makes insufficient lactase, which is the enzyme that breaks down the milk sugar lactose.

In addition, while those with a milk allergy should avoid all milk products, a person with lactose intolerance may get insufficient calcium from their diet and benefit from eating yogurt.

About 36% of people in the United States have difficulty digesting lactose.

Learn more about lactose intolerance here.

Symptoms

Undigested lactose passes into the colon, where it begins to ferment, causing the symptoms of lactose intolerance, such as:

  • bloating
  • diarrhea
  • gas
  • stomach pain

Causes

Lactose intolerance can be genetic or have a secondary cause, such as:

Lactose intolerance presents on a spectrum, with some people tolerating dairy products better than others. Research indicates that some people could consume up to 12 grams of lactose with no significant symptoms.

In addition, the National Institute of Diabetes and Digestive and Kidney Diseases note that the condition is less common among people from Europe or with family from Europe. They say that in the U.S., people belonging to the following racial and ethnic groups are more likely to have trouble digesting lactose:

  • Hispanic
  • Latinx
  • Asian American
  • American Indian
  • African American

Alternatives

Some people with lactose intolerance may tolerate milk products lower in lactose, such as yogurt and hard cheeses.

The straining of Greek yogurt during processing removes whey, making the product naturally low in lactose. It also creates a firm texture.

A 2018 review of the nutrient content of a range of yogurts found that Greek yogurt had the lowest quantity of sugar, of which 80% is lactose. Greek yogurt may, therefore, be a suitable option for someone with lactose intolerance.

Treatment

People should talk with their doctor or dietitian about managing their diet to minimize lactose intolerance symptoms. The dietitian may also recommend lactase replacement pills.

Most grocery stores now carry a range of alternatives to dairy products that allow people to avoid cow’s milk and products that contain it. People can purchase plant-based dairy-free butter and margarine, milk, yogurt, and cheese.

Depending on an individual’s diagnosis, they may also have to avoid milk from other animal sources, such as goat’s milk, which could cause a similar allergic reaction.

In the U.S., milk and milk products must appear on the list of ingredients. People can carefully read this list and check for any possible allergens, such as the milk proteins casein and lactoferrin, which may not immediately stand out as problematic.

If an individual suspects that they have a yogurt allergy, they should seek medical advice for an accurate diagnosis. The doctor may want to run further tests, such as a skin prick test, to determine whether the individual has a milk allergy or lactose intolerance.

A skin prick test involves placing a small amount of liquid containing the dairy allergen under the skin of the arm or back. If a red lump appears, this may suggest an allergic reaction. The doctor may also take a blood test to measure antibodies.

Anyone experiencing severe symptoms that could indicate anaphylaxis, such as trouble breathing, should seek emergency medical attention or dial 911.

An allergy to milk products is typically the cause of a yogurt allergy. If someone has a milk allergy, the cornerstone of treatment is dietary management to avoid milk and milk products.

Lactose intolerance is another condition that could cause similar symptoms to a milk allergy. If an individual is experiencing symptoms after eating certain foods, they should talk with their doctor to determine the next steps.

However, severe symptoms, such as trouble breathing or low blood pressure, could indicate anaphylaxis. In this case, a person will need emergency medical attention.