An Overview of Milk Allergy

Different Types of Dairy Allergies

Baby girl feeding on milk with a milk bottle
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Milk allergies, also described as dairy allergies, are the most common food allergy in children and adults. An allergy to cow's milk is generally evident within the first year of life. Children who are allergic to milk can develop symptoms such as a rash, stomach upset, vomiting, and swelling.

People with a milk allergy develop these symptoms because the immune system reacts to substances in the milk. If your child has a milk allergy, this is different from lactose intolerance, a very common problem which is caused by a deficiency in lactase (an enzyme that breaks down the lactose protein in milk).

Milk is rich in protein and calcium. If your child can't have milk because of an allergy, there are many dairy-free sources of these nutrients, and your child will probably like at least a few of the options.

Symptoms

An allergic reaction to dairy products may cause immediate effects or a delayed reaction after consuming milk. There are a number of different symptoms that can develop.

Common effects of a milk allergy can include any of the following:

  • Eczema itchy, red patches on the skin
  • Hives
  • Abdominal pain and discomfort
  • Digestive problems
  • Pain when swallowing
  • Diarrhea
  • Vomiting
  • Blood-streaked stools
  • Nasal allergy symptoms, such as a runny nose and watery eyes
  • Asthma symptoms, such as wheezing

Milk Allergies in Infants

Babies don't have the ability to complain, so manifestations of a milk allergy can be hard to recognize. A child might be fussy, irritable, and cry. Because babies eat every few hours, it is always clear that the symptoms are related to eating.

Children may eventually experience weight loss due to digestive problems, vomiting, and diarrhea. Keep track of your baby's weight gain—stagnating weight or weight loss is typically described as failure to thrive, which is a serious problem that can affect a baby's development for the long term.

Complications

Generally, milk allergies are not life-threatening. But some children experience have severe reactions to milk.

Signs of a milk allergy-induced medical emergency include:

  • Wheezing or difficulty breathing
  • Swelling around the mouth or lips
  • Anaphylaxis

Heiner syndrome is a type of milk intolerance. It is not an allergy, and it manifests with coughing, ear infections, spitting blood, and/or weight loss.

Causes

If you or your child has a milk allergy, dairy products can trigger your allergies by activating your immune system. Milk is present in a number of different foods, such as butter, cheese, ice cream, pudding, yogurt, custards, candies, sauces, granola bars, and protein powders.

Many foods may not list milk as an ingredient, but clearly state that they contain lactic yeast, ghee, whey, curd, or casein—all of which are made from milk.

Keep in mind that even flavored foods, such as butter-flavored popcorn or chocolate-flavored desserts, may contain some milk. Similarly, dairy substitutes, such as artificial cheese or margarine, may contain milk as well.

Surprise sources of milk can include deli slicers, which are used to cut meats and cheese. And breaded foods like meat, vegetables (like tempura), and seafood may be dipped in milk.

There are several physiological mechanisms that facilitate an allergic reaction to milk.

Immunoglobulin E (Ig-E)- Mediated Milk Allergy

Ig-E is a type of antibody produced by your immune system. These antibodies activate immune cells and cause them to release histamine and other chemicals that cause inflammation.

Symptoms of classic Ig-E mediated food allergies typically appear within 15 to 30 minutes of eating, and can include skin reactions, respiratory problems, or digestive issues.

Eosinophilic Gastrointestinal Disorders

Eosinophils are a type of white blood cell that is typically present in low numbers in the digestive tract. With an eosinophilic gastrointestinal disorder (EGID), these cells multiply, and they may attack the body when exposed to an allergy trigger.

Eosinophilic gastrointestinal (GI) disorders include:

  • Eosinophilic esophagitis, EoE, (eosinophils are primarily located in the esophagus)
  • Eosinophilic gastritis (eosinophils are primarily located in the stomach)
  • Eosinophilic gastroenteritis (eosinophils are primarily located in the stomach and small intestine)
  • Eosinophilic colitis (eosinophils are primarily located in the colon)

EoE is the most common of these types. Symptoms of eosinophilic GI disorders may include trouble eating, diarrhea, and failure to thrive.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

FPIES is a severe, systemic reaction to food that usually develops in infants within the first months of life. It is often described as food intolerance, rather than an allergy.

Infants can develop this reaction from breastmilk or from some types of formula. It may also include a reaction to other foods besides milk, such as fruit, vegetables, potatoes, and/or seafood.

This type of reaction generally causes digestive issues, such as vomiting, diarrhea, and blood-streaked stools. It rarely causes systemic shock, which is characterized by very low blood pressure, heart failure, loss of consciousness, and is life-threatening.

Children usually grow out of FPIES by age three.

Genetics


Rates of dairy allergy vary widely in different parts of the world.

For example, the prevalence of dairy allergies in different countries is:

  • United States: 1% to 2.5% of children under 6
  • Israel: less than 1% of children
  • Australia: More than 10% of one-year-olds

It is not clear why there are such different regional rates of dairy allergies. There may be a genetic component contributing to the development of dairy allergies, but there is no single gene that has been found to be responsible.

Diagnosis

It can be hard to know whether your child has a dairy allergy or whether they have another illness, such as digestive issues or a GI infection.

Before your child's scheduled appointment with a pediatrician or allergist, it helps to keep a food diary and record your baby's symptoms. Along with a medical history and your child's physical examination, several methods are used to diagnose milk allergies.

Oral Food Challenge

A common way of identifying food allergies is with a food challenge. This is a test in which you would eliminate milk from your child's diet for a few weeks, and then a small amount of milk would be introduced in the doctor's office to observe your child's reaction.

An oral food challenge is the most reliable way to identify FPIES, and it is also used in the diagnosis of IgE mediated dairy allergies and EGIDs.

Since there is a possibility of a severe reaction, oral food challenge should only be done in a medical setting.

Skin Prick Test

A skin prick test, also commonly called a scratch test, involves placing a sample of milk on the skin. A skin reaction within 15 minutes is indicative of a milk allergy. However, because milk allergies are triggered by eating dairy rather than by touching milk, a negative reaction (no reaction) does not rule out a milk allergy.

Blood Test

A blood test can identify high levels of immune cells and IgE, which may be suggestive of an allergy. However, EGIDs and FPIES may be associated with high levels of inflammatory cells, but not necessarily with high levels of IgE.

Endoscopy and Colonoscopy

EGIDs may cause changes in the digestive organs, which can be seen with interventional tests such as endoscopy or colonoscopy. Endoscopy is a test in which a tube with a camera is placed in the mouth to look at the upper parts of the digestive system, while colonoscopy is a test in which a tube with a camera is placed in the rectum to observe the colon.

Treatment

There is not a cure for milk allergies. The best management for all types of milk allergies and milk sensitivities is strict avoidance of dairy products. Since many infants develop milk allergies before being introduced to solid foods, your child's doctor may prescribe a hypoallergenic infant formula for your baby.

Because the allergic reaction generally does not last for a long time, medication is not standard. However, if your baby has a persistent reaction after dairy exposure, you should call your child's pediatrician.

Breastfeeding

Many lactation consultants will suggest that a breastfeeding mother avoid dairy products if the baby is fussy, gassy or has symptoms such as eczema.

The concern about elimination diets for breastfeeding mothers is that mothers need lots of nutrients to produce an adequate supply of milk and to maintain their own health while breastfeeding. Therefore, if you are considering an elimination diet, talk to a dietitian about how you can continue to eat a healthy, balanced diet without dairy.

Prevention

It may not be possible to prevent food allergies, but there are ways to lower your baby's risk of developing allergies. If your family has a history of food or environmental allergies, discuss feeding options with your pediatrician or an allergist before your baby is born.

Babies who are considered at-risk for developing food allergies may be less likely to develop food allergies if they are exclusively breastfed or fed for the first 4 months of life.

A Word From Verywell

Milk allergies are the most common food allergies. Because milk is rich in nutrients, it is important to plan out your diet carefully if you have to avoid dairy.

Keep in mind that increased tolerance to milk is common as children reach adolescence and adulthood. So even if your baby is allergic to milk, it may not be forever. However, there is no reliable way to predict whether your child will outgrow their milk allergy, so retesting can be beneficial.

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