Food allergy occurs in approximately 4 percent of adults and in 6 to 8 percent of children under 4, according to the National Institutes of Health. Milk protein allergy is one of the most common types of food allergy in children, though most children outgrow the allergy by age 3.
Allergy to milk proteins occurs as the result of an immune system malfunction. The immune system mistakenly identifies milk proteins as a dangerous substance and forms antibodies called immunoglobulin E (IgE) against the proteins. When the person encounters milk proteins, these antibodies recognize them and release a number of chemicals that result in the symptoms of an allergic reaction. The proteins that the immune system recognizes are casein and whey.
The symptoms of a milk protein allergy typically occur a few minutes to an hour after ingestion of milk products. Initial symptoms may include a skin rash or hives, which are itchy red bumps. The person may develop symptoms of wheezing or shortness of breath, and nausea or vomiting can result as well. In severe cases, a life-threatening reaction called anaphylaxis can occur. If symptoms of hives, difficulty breathing or vomiting occur after ingestion of a food, medical care should be sought immediately.
Those who are at increased risk for development of milk protein allergy include people with other allergies, atopic dermatitis or a family history of allergy. Other allergies can include other food allergies, asthma or symptoms of runny nose and sneezing in response to environmental allergens. Children are more likely to develop allergies to milk protein than adults, though the allergy can develop at any point in time.
An allergist can often determine whether a milk protein allergy exists by conducting a detailed discussion of the events leading up to the allergic reaction. If it seems likely that a milk protein allergy is present, testing can be conducted. Skin-prick testing is common and involves scratching a small amount of the allergen onto the surface of the skin and then measuring the skin reaction. If this test is positive, blood testing to measure the level of IgE that has formed against milk protein may be conducted.
The primary treatment of milk protein allergy is avoidance of milk protein. This includes avoidance of milk, yogurt, cheese and all products that contain milk protein. Injectable epinephrine is also prescribed, as this can reverse an allergic reaction in case of an accidental exposure. If the injectable epinephrine is used, the person must obtain medical attention immediately.
Allergy to milk protein is different than lactose intolerance, though some symptoms may be similar. Lactose intolerance may cause symptoms of stomach discomfort, flatulence and diarrhea but is not an allergic reaction and does not carry the risk of a life-threatening reaction. Lactose-free dairy products are suitable for people with lactose intolerance but not for those with a milk protein allergy. Many people who are allergic to milk protein are also allergic to sheep, goat and buffalo milk. Soy milk is typically a good alternative for these people.