Living with a milk allergy
What is a milk allergy?
A milk allergy is a condition in which milk and milk products trigger an inappropriate immune system response.
When milk is consumed, the body's immune system sees proteins in the milk as dangerous invaders and responds by releasing antibodies called immunoglobulin E (IgE) to 'fight off' the food. These antibodies trigger the release of other chemicals, most importantly histamine.
This overreaction by the immune system leads to a number of symptoms, ranging from uncomfortable to life threatening.
Around 80% of the proteins in milk are found in the curd - the substance that forms hard chunks in sour milk - and the remaining 20% in the watery part of milk called whey.
A few people may develop milk allergy where the immunoglobulin E (IgE) antibody is not involved and where symptoms develop more slowly, called non-IgE-mediated milk allergy.
How common is milk allergy?
Cows' milk allergy is quite common in young children, affecting about one in 50 infants. It is much less common in adults, with up to 1 in 200 having the condition.
A milk allergy should not be confused with lactose intolerance, which is a food intolerance not a food allergy. Lactose intolerance is the inability to digest the sugar contained in milk, which is called lactose.
What are the symptoms of milk allergy?
Symptoms can affect any of three different areas of the body. These are:
- The skin: Red itchy skin, swelling of the face and around the mouth
- Gastrointestinal tract: A feeling of narrowing in the throat, abdominal pain and spasms, nausea, vomiting, stomach cramps, and diarrhoea
- The respiratory tract: Wheezing, coughing or shortness of breath, a tight chest, a croaky or hoarse voice, sneezing, runny nose, nasal congestion
A few people may have a very extreme reaction called anaphylaxis. This severe allergic reaction causes swelling in the airways leading to the lungs, resulting in an inability to breathe. This may be accompanied by a drop in blood pressure with the risk of unconsciousness.
Anaphylaxis is a medical emergency that requires urgent treatment.
How is milk allergy diagnosed?
Your GP will ask some questions about your symptom, such as how long they took to develop after consuming milk products, how long the symptoms lasted and how severe they were. You may also be asked whether there is a family history of allergies.
If your GP suspects that an allergy is involved, you may be referred to an allergy clinic for further tests.
In cases where symptoms began quickly, a skin-prick test can determine whether milk was responsible. A small needle is pushed through a drop of milk and into the skin. If the area becomes swollen, red and irritated, milk proteins are likely to be the cause of the allergy.