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An allergic reaction manifests as a variety of symptoms that are usually detected in response to consuming a food containing dairy. A dairy allergy, is often referred to as a cow milk allergy by doctors, is a common diagnosis.

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A dairy allergy occurs when an individual’s body produces an immune response to one or more of the proteins found in animal milk. While cow milk is the most common dairy, these allergies can also be in response to consuming other animal milk, such as goat or sheep milk.

This condition appears to affect 2–3% of infants and often disappears by the age of 6, causing the prevalence to fall to around 1%. However, adult allergies tend to be lifelong.

The symptoms can vary from mild to life threatening anaphylaxis. A person should consult an emergency department immediately if this severe reaction occurs.

Read this article to learn more about the symptoms, causes, management and treatments, and more.

Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:

  • hives
  • swelling of the face or mouth
  • wheezing
  • fast, shallow breathing
  • a fast heart rate
  • clammy skin
  • anxiety or confusion
  • dizziness
  • vomiting
  • blue or white lips
  • fainting or loss of consciousness

If someone has these symptoms:

  1. Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
  2. Dial 911 or the number of the nearest emergency department.
  3. Lay the person down from a standing position. If they have vomited, turn them onto their side.
  4. Stay with them until the emergency services arrive.

Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.

Symptoms of a dairy allergy usually appear within a few minutes to a few hours after dairy consumption.

Symptoms are similar regardless of age but can differ based on the individual. Some people have mild reactions, but others may have more extreme reactions. Scientists are not sure why some people have more severe reactions than others.

Rapid onset symptoms that occur within 1 hour of consuming dairy can include:

Anaphylaxis is a medical emergency that requires prompt treatment, so dial 911 if someone is experiencing it.

Slow onset symptoms, which take longer to show up, can include:

  • diarrhea
  • blood in the stool
  • abdominal cramps
  • colic (in infants)

A dairy allergy and lactose intolerance often present with similar symptoms, making it difficult to differentiate the two conditions.

However, a person must recognize the difference between a dairy allergy and lactose intolerance to treat their symptoms appropriately. A doctor can diagnose either condition.

The major difference between the two conditions is that a dairy allergy causes the body to have an immune reaction, while lactose intolerance is an issue with the digestive system.

After consuming dairy, common symptoms of lactose intolerance include:

  • gas
  • bloating
  • diarrhea

Lactose intolerance is a digestive condition in which an individual’s body is deficient in lactase. Lactase is a digestive enzyme that breaks down the milk sugar lactose. When an individual does not have any lactase and they consume dairy, this can cause gas, gastrointestinal discomfort, and diarrhea.

Read more about lactose intolerance.

When a person experiences an allergic reaction to dairy, it is a result of how their body reacts to certain proteins present in the dairy product. Two of the main proteins in milk — whey and casein — can cause an allergic reaction in some individuals.

When a person with a dairy allergy consumes dairy, the body’s immune system:

  1. responds to a specific milk protein
  2. triggers an immune response
  3. attempts to neutralize the protein

The next time that the body comes into contact with the protein, the immune response recognizes it.

The body will react to the dairy protein and produce antibodies called immunoglobulin E (IgE). When the body produces IgE antibodies, it releases certain chemicals, such as histamines, that result in an allergic reaction. This results in the symptoms associated with an allergy, such as a rash or trouble breathing.

Individuals with a dairy allergy should avoid consuming dairy products and foods containing dairy.

In order to avoid a serious reaction, follow these precautions:

  • Check food ingredients: To ensure that individuals who are allergic to dairy avoid foods containing it, it is important to look over the ingredients in processed foods. People can often find milk proteins in unexpected foods, such as some chewing gums, salad dressings, breads, other baked goods, and more. Ingredients such as whey and casein, along with any ingredient with the prefix “lac,” have milk proteins that may cause an allergic reaction.
  • Ask about food preparation: When eating at a restaurant or outside of the home, individuals should inquire about the ingredients in the food as well as the food preparation.
  • Take antihistamines: If the allergic response is mild, an individual may simply take an over-the-counter antihistamine to help ease the symptoms.
  • Inject epinephrine: Some individuals who have a more severe reaction to dairy may need to inject epinephrine. Individuals who have more severe reactions should carry epinephrine at all times.

Read more about allergies from our hub.

There are some factors that may increase the likelihood that an individual will have a dairy allergy. These include:

  • Age: Research estimates that around 7% of infants under 1 year of age have a dairy allergy.
  • Family history: Allergies are three times more likely in infants with a family history of an allergy.
  • No pets in the home: Fewer allergic manifestations occurred later in life for children who lived with an increasing number of household pets.
  • Shorter period of breastfeeding: Infants who are breastfed for a shorter period are more likely to develop the allergy. Research from 2017 shows there is reduced allerg risky in infants who have continued drinking breast milk.
  • Other allergies: The presence of other allergies may lead to children developing other allergic conditions, such as eczema and asthma.
  • Food before 4 months old: Infants who consume foods before 4 months of age are at a higher risk of developing the allergy than infants who are only breastfed until 6 month of age or older.

Individuals or those with children who experience discomfort, a rash, or other symptoms of an allergic reaction after consuming dairy should speak with their primary care physician to determine the cause of this reaction.

If an individual has a more severe reaction, such as difficulty breathing or swelling of the face and throat area, they should seek medical attention immediately.

Individuals with a dairy allergy may also have an allergy to other animal-based products, such as goat milk, and plant-based alternatives, such as soy milk.

There are many plant-based alternatives to cow milk that people can buy online, including:

  • soy milk
  • almond milk and other nut milks
  • rice milk
  • hemp milk
  • oat milk
  • coconut milk

Read more about dairy alternatives.

Human breast milk is a great option for infants younger than 1 year old who are not yet consuming whole foods. However, if human breast milk is not an option, other options include:

  • soy protein formula
  • hypoallergenic formula (removes milk protein)
  • amino acid-based formula

Also, sometimes infants can have an allergic reaction to breast milk after the nursing parent consumes dairy. Parents who notice this or have infants that are allergic to dairy may want to consult with a doctor to determine the best alternative formula.

Individuals with dairy allergies can live normal lives. However, they will need to avoid dairy products and foods that contain dairy proteins in order to avoid an allergic reaction.

While many children can outgrow a dairy allergy, most allergies in adults do not disappear over time, so an adult with a dairy allergy will likely have it for the rest of their life.

Because of this, these individuals should consult with their doctor to develop a plan. It is important that these individuals know how to use injectable epinephrine in case they experience anaphylaxis, a severe reaction.