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Digestive Disorders > Intolerances > Lactose Intolerance

Milk protein allergy

Dr. med. André Sommer

Dr. med. André Sommer

For many people, cow's milk products are an integral part of daily nutrition. If symptoms occur during consumption, this is usually due to an intolerance to the lactose. In very rare cases it may also be a milk protein allergy. With this food allergy, the immune system reacts to the cow's milk protein casein. Milk protein allergy usually affects young children. It is estimated that two to three percent of infants under the age of three are affected. However, the allergy usually disappears over the years. It rarely persists into adulthood. And it hardly arises in adults; lactose intolerance is more common.

What are the symptoms of a milk protein allergy?

If there is an allergy to cow's milk protein, an allergic reaction occurs when eating foods containing cow's milk. The possible symptoms are:

  • Gastrointestinal complaints Nausea, vomiting, abdominal pain, diarrhea
  • Itchy skin reactions (eczema)
  • Allergic reaction (anaphylaxis): Drop in blood pressure, swelling of the tissues (edema)

The symptoms of milk protein allergy are not limited to the gastrointestinal tract. Sudden allergic (anaphylactic) reactions can lead to a drastic drop in blood pressure. Tissue swellings (edema) can also occur. If the airways swell, this is life-threatening. The anaphylactic reaction can also lead to asthma and, in severe cases, heart failure. These complications make milk protein allergy a threatening clinical picture.

Early symptom of anaphylactic reaction with food allergies:

  • Itching in the throat and throat: This early sign definitely shouldn't be ignored!

Why does milk protein allergy mainly affect infants?

Young children in particular are at high risk of developing a food allergy. Cow's milk allergy in particular arises in the first two months of life. The intestinal mucosa actually prevents large molecules that can trigger allergies from being absorbed. As a result, large food molecules are only split into smaller molecules. In infancy, however, this barrier function of the gastrointestinal tract is not yet fully developed. This means that even large substances can be absorbed through the intestinal mucosa and cause an allergic reaction of the immune system. Most of the time, the food allergy disappears with aging. The risk of food allergy increases if the family already has food allergies (family disposition).

Food allergies - overview:

  • Occur mainly in childhood
  • In childhood: Cow's milk, chicken eggs, fish
  • In adulthood: Nuts, fish, peanuts, fruits

My baby has a cow's milk allergy. Can I still breastfeed?

Even if your baby has only been breastfed so far, it can develop a milk protein allergy. But your baby is not allergic to breast milk. It reacts to the cow's milk proteins, which are transmitted through breast milk. If the pediatrician suspects a cow's milk allergy in your child, you can continue breastfeeding. However, you have to avoid milk and milk products from now on. Through the dairy free diet, your baby's symptoms should improve. After two weeks, the so-called provocation test is carried out under medical supervision. If the diagnosis of milk protein allergy is confirmed by a new reaction, you should continue to avoid cow's milk. Since the allergy usually disappears again, a further provocation test is recommended after six to eighteen months.

Did you know?

The protein casein in cow's milk is not species-specific. It is contained in different types of milk. However, sheep or goat milk are well tolerated with a cow's milk protein allergy and are a good alternative in addition to plant-based replacement products.

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How do I diagnose a milk protein allergy?

If gastrointestinal complaints occur after eating, intolerance or allergy is suspected. Especially in toddlers, the symptoms mentioned should be considered a milk protein allergy. Diagnostics are made up of various components:

1. Detailed symptom survey (anamnesis):

  • Type, number and severity of attacks after eating
  • Symptom diary: Which foods are suitable?
  • How is food intake related to the reaction?
  • Within seconds (early reaction): Itching and swelling of the mouth
  • Seconds to minutes: Nausea and vomiting
  • Minutes to hours (late reaction): Colic, diarrhea, skin reactions, asthma

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2. Skin test (e.g. prick test):

The reaction of the skin is tested here by scratching it with small stitches that contain the allergen. However, this test is not very meaningful for cow's milk allergy

  • Laboratory examinations: Determination of specific IgE antibodies (this shows sensitization to the milk protein allergen, but is not evidence!)
  • Fasting: The allergy-causing food is left out of the daily diet and symptoms disappear
  • Provocation testing: Symptoms occur again with the consumption of cow's milk. This proves the presence of the allergy

Keep in mind!

The risk of an anaphylactic reaction is particularly high if you have already reacted to food repeatedly and have allergic asthma!

In the provocation test, milk is administered under medical supervision after a two-week maternity leave. If there is a milk protein allergy, the gastrointestinal symptoms described, such as rashes and swellings, will occur again. As there can also be a shortage of air in severe cases, it is very important not to carry out the provocation test at home! It can even be fatal with severe allergic reactions!


A food allergy is present when symptoms appear after eating, which have disappeared during maternity leave and reappear in a controlled provocation.

What foods are banned in people with milk protein allergies?

With a milk protein allergy you have to dispense with all milk products. The smallest quantities of cow's milk protein can cause a severe allergic reaction. And this can be life-threatening!

For finished products, you should therefore always check the list of ingredients to see whether milk is listed as an allergen. Products that contain cow's milk include:

  • Fresh milk, long-life milk
  • Lactose-free milk
  • Yogurt, curd cheese, cream, pudding
  • Cream cheese
  • All types of cheese
  • Chocolate
  • Sauces
  • Salad dressing
  • Soups
  • Finished products


Vegan products do not contain animal proteins and are therefore tolerable for people with allergies to cow's milk

I am afraid of a severe allergic reaction. What can I do?

Always make sure that you do not consume milk protein in the restaurant or with finished products. Have you ever had a strong anaphylactic reaction to cow's milk? Then it is recommended you always keep an emergency kit with you. This includes an adrenaline shot, an antihistamine and a glucocorticoid. All three agents treat physical reactions during a severe allergic attack. If you only have gastrointestinal complaints, you do not need to use these medications. The symptoms are uncomfortable, but not dangerous.

Terjung, B. and Lammert, F., 2007. Laktoseintoleranz: neue Aspekte eines alten Problems. Dtsch Med Wochenschr, 132(06), pp.271-275. Downloaded on 10.08.2018 from:

Birkholz, T., Schmidt, J. and Schnelke, A., PO 2.4. 7 Hämatemesis bei einem Neugeborenen-ein beängstigender Einsatz? Downloaded on 10.08.2018 from:

häufig sind Kuhmilcheiweißallergien, W., 2009. Kuhmilcheiweißallergie–immer noch zu selten erkannt. Allergo J, 18, p.586. Downloaded on 10.08.2018 from:

Dr. med. André Sommer

Dr. med. André Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara Care.

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