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Milk Allergy: Symptoms, Causes and Treatment

A milk allergy is an adverse reaction of the body’s immune system to one or more proteins found in milk. It is one of the most common food allergies and can be potentially fatal. The only way of successfully treating a milk allergy is to completely remove milk and dairy products from the diet. However, a milk allergy should not be confused with lactose intolerance, which is a sensitivity to the sugar found in milk products. Lactose intolerance does not involve the immune system and is usually less severe than milk allergy.

An allergic reaction to milk usually occurs when the milk protein is consumed, but it can also occur when an allergic person absorbs milk protein through the skin (e.g., from latex gloves). Once the protein is inside the body, an adverse reaction is triggered as the immune system misinterprets this common harmless protein as a dangerous substance.

Milk allergies are most common in little babies, who usually develop them within the first six months of life. But, 70-80% of infants with milk allergies outgrow the condition by the age of four, though some milk allergy conditions persist throughout adulthood. In fact, it is rare for an adult to develop a milk allergy.

Symptoms of Milk Allergy

Symptoms of a milk allergy may range from mild allergic reaction involving symptoms from two or more body systems mentioned later in this section to life-threatening anaphylactic shock, which involves lowered blood pressure and breathing problems. The symptoms usually occur in one of two different ways, including:

  • Rapid onset. An allergic reaction occurs only a few minutes after consuming a milk protein and can be deadly if not properly treated.
  • Slower onset. This reaction occurs several hours after ingesting milk protein. Symptoms often involve the gastrointestinal system. This type of reaction to a milk protein is more common than rapid onset.

The symptoms of milk allergies are the same as with other food allergies and most commonly include:

  • Hives
  • Skin rash
  • Eczema
  • Swelling around the mouth and lips
  • Diarrhea
  • Nausea
  • Vomiting
  • Bloated sensation
  • Abdominal cramps
  • Wheezing
  • Asthma

Potential Causes and Risk Factors for Milk Allergy

There are several types of proteins present in cow’s milk and each one of them can be responsible for triggering milk allergies whether found in the solid curd or whey. An individual can be allergic to one or more proteins from either part or both parts.

Milk proteins are found in many types of foods. Therefore, patients with a milk allergy must carefully check the ingredients of all foods before they are consumed. This is a list (though not complete) of common ingredients that may contain milk proteins:

  • Brown sugar flavoring
  • Butter, butter fat, butter oil, buttermilk, artificial butter and butter solids
  • Calcium
  • Caramel color or flavoring
  • Casein, caseinate and rennet casein
  • Cheese
  • Cottage cheese
  • Cream
  • Curds
  • Custard
  • Ghee
  • Half and half
  • High protein flour
  • Ice cream
  • Lactalbumin, lactoglobulin, lactulose and lactalbumin phosphate
  • Lactose
  • Milk, including dry milk, condensed milk, evaporated milk, malted milk, powdered milk, milk solids and milkfat
  • Nougat
  • Pudding
  • Sour cream, sour cream solids, sour milk solids
  • Whey
  • Yogurt

Milk proteins are also present in a number of unexpected places, including:

  • Bread and breaded foods (often fried)
  • Canned tuna fish
  • Chewing gum
  • Chicken broth
  • Chocolate
  • Hydrolyzed vegetable protein
  • Margarine
  • Processed meats (e.g., salami, hot dogs, sausage, bologna, pepperoni)
  • Soy cheeses

Some medications use the milk sugar lactose as a filler. Because small amounts of some milk proteins can be found in lactose, highly sensitive individuals with milk allergies may also have allergic reaction from such medications. In addition, the milk protein casein can be found in several kinds of latex gloves. Skin contact with this protein can trigger an allergic skin reaction in many patients with a milk allergy.

Milk allergies tend to be passed on genetically. Often, a child that comes from a family with a history of allergies, especially a food allergy, is more likely to have a milk allergy. In addition, parents that have a history of allergic rhinitis or eczema seem to have an increased risk of producing children with allergies. There is some evidence that method of birth may also influence a child’s reaction to milk. Children delivered by Cesarean section are at increased risk of developing a milk allergy or lactose intolerance.

Related Allergies and Conditions

Lactose intolerance. A milk allergy is often confused with lactose intolerance as both of these conditions are triggered by milk. However, lactose intolerance is not an allergy because it does not involve an exaggerated response by the immune system to a harmless substance that, in most people, does not cause any reaction. For more information on lactose intolerance and its symptoms please refer to this post.

Food poisoning can also be mistaken for a milk allergy because it often produces very similar symptoms such as nausea, vomiting, diarrhea and abdominal cramps.

Latex allergy can share certain symptoms of a milk allergy, sometimes complicating its diagnosis. Although both are true allergies that involve an immune system reaction, latex allergies are typically triggered by external contact with latex, which involves several proteins present in this natural rubber, or occasionally by inhaling latex particles that have become airborne.

Calcium deficiency. Because patients with a milk allergy need to completely remove milk and dairy from their diets, a calcium deficiency may result. Calcium deficiency causes bone weakening (osteoporosis) and can lead to skeletal abnormalities. Fortunately, foods such as dark leafy greens, fish, orange juice and soy foods can replace the missing calcium.

Diagnosing Milk Allergy

The tests used to diagnose milk allergies are very similar to those used to identify other food allergies. If milk is already a suspected allergen trigger, it is relatively simple to diagnose a milk allergy. Generally, a physician will first create a detailed medical and dietary history of the patient. A physical examination should help identify or exclude medical problems that may be responsible for the patient’s symptoms. In order to be sure that milk is the culprit, one or more of the following tests will be administered:

  • Skin test. This test involves pricking or injecting a patient’s skin with milk protein. If an allergy is present, the tested area will react with redness or swelling.
  • RAST (radioallergosorbent test). This blood test is used to detect antibodies in a patient’s blood sample that correspond to a milk allergy.
  • Elimination diet. Milk is removed from an individual’s diet for several weeks to see if allergic reactions persist.
  • Oral food challenge. The patient consumes several capsules with different foods without knowing which capsule contains the suspected allergen. A doctor then looks for signs of a milk allergy.

Treatment of Milk Allergy

At the moment, the only treatment for milk allergy is the complete removal of milk and all products containing milk protein from the diet. Patients must check ingredient lists for milk and milk products diligently because food allergies can be deadly. Food manufacturers are now required by the FDA to clearly list food allergens on their product labels. However, anyone with a milk allergy should be particularly vigilant when eating away from home. In addition, some manufactured items, such as latex gloves, also contain milk proteins and must be avoided by milk-allergic individuals.

Also, a mother nursing an infant that has a milk allergy must avoid her own milk and dairy consumption because small amounts of cow’s milk proteins can cross over into breast milk (which is generally not allergenic).

It should be noted that the phrase “non-dairy” on the packaging of a food does not mean the food is milk-free (it can still contain 0.5% of milk by weight). In addition, dairy products marked as “lactose-free” do contain milk proteins and can, therefore, trigger a milk allergy.

Following a milk-free diet can lead to nutritional deficiencies – particularly in calcium and vitamin D. Certain nutrient-rich foods (e.g., fish, green leafy vegetables, eggs, soy foods) can help replace these missing nutrients.

A number of alternatives are currently available to patients with milk allergies who wish to drink milk or eat dairy, including various types of alternative milk (e.g., rice milk, soy milk, goat’s milk, sheep’s milk) and non-dairy substitutes (e.g., cheese, tofu, yogurt, ice-cream, chocolate). Unfortunately, some people who are allergic to cow’s milk proteins are also allergic to proteins found in other types of milk.

Relief of Symptoms Associated with Milk Allergy

At present, there are no medications available that could prevent a milk allergy from taking place. All current treatments are aimed at relieving allergy-related symptoms that affect the nose, throat, skin, lungs and gastrointestinal tract. These symptoms can be treated with several types of drugs, including antihistamines, corticosteroids and bronchodilators (incl. epinephrine injections). However, these medications should not be taken to prevent an allergic reaction. Avoidance is the only safe method of preventing an adverse immune reaction to a food allergen such as milk protein.