If you have a cow's milk allergy, you are allergic to one of the many proteins in milk, often casein or whey protein. It means that you can’t tolerate milk and should avoid any kind of milk or dairy products.
A milk allergy is a malfunction in an abnormal overreaction by the body's immune system to milk protein. Milk protein is normally harmless, but if you have a milk allergy, your immune system will react to milk protein as if it is a sickness that it needs to get rid of. If you have a milk allergy, you should therefore avoid milk, yogurt, cheese, butter and all other types of dairy or products containing milk protein.
Between 2% and 6% worldwide are estimated to be allergic to milk protein according to the UN's Food and Agriculture Organisation FAO. However, while a milk allergy is developed within the first year of a baby's life, most children will have outgrown the milk allergy by the time they are five years old.
Milk allergy vs lactose intolerance
Some people confuse a cow's milk allergy with lactose intolerance, but the two conditions are very different, both in terms of the root cause and in terms of the severity of the symptoms.
While a milk allergy is related to the immune system and milk protein, lactose intolerance is caused by low levels of lactase in the digestive system, which makes it difficult for you to digest lactose. It can lead to unpleasant symptoms such as stomach pain or bloating, and even if these symptoms can be uncomfortable, they are usually harmless.
Read more about lactose intolerance.
Symptoms of milk allergy in infants and adults
The milk allergy symptoms in babies as well as older children are similar to thos of a milk allergy in adults. It will usually show immediately after drinking milk or eating dairy. Sometimes, however, the milk allergy reaction can appear later. The symptoms of a milk allergy span from mild to life threatening.
Common milk allergy symptoms are:
- Nausea or vomiting
- Stomach ache, colic, diarrhoea or constipation
- Itchy hives, welts or skin rash
- Swelling of eyes and lips
- A runny or blocked nose
In extreme cases, you can get a serious allergic reaction, anaphylaxis, that can potentially stop your breathing and will require urgent medical help. You should always seek advice from your doctor if you think you or your child are allergic to milk protein.