Milk allergy is a food allergy where a person is allergic to the proteins present in milk.

Pathophysiology

On the one hand, the immune system protects the body from harmful foreign invaders such as bacteria and viruses and mounts a response to effectively killing them off. However, on the other hand, too much activation of the immune system, especially against foods, can lead to discomfort and complications. Peanuts, shell fish and several other food items are known to cause allergies.

Milk allergy is also called cow milk allergy since the allergy is more commonly seen with cow's milk than with other forms of milk.

Milk allergy and milk intolerance

Milk allergy refers to an immune reaction which occurs in response to milk ingestion whereas milk intolerance refers to a difficulty in digesting milk. The features of milk allergy such as hives and wheezing differ somewhat from those of milk intolerance which typically causes bloating and flatulence.

Who gets milk allergy

Cow's milk allergy is most common among young children, occurring in around 2% of all infants in developed countries. Milk allergy usually first manifests when a baby is weaned off breast milk and is introduced to cow's milk. Most children overcome the allergy by time they are 3 years of age but some continue to have symptoms and react severely to milk ingestion for the rest of their life.

Symptoms of milk allergy

Some common symptoms of milk allergy in babies include:

• Severe colic in the abdomen
• Vomiting
• Crying
• Refusal to feed
• Development of nettle rash or hives
• Swelling of the face, lips and tongue
• Skin allergies such as atopic dermatitis, typically around the mouth or diaper area
• Cough, wheezing and swelling in the throat or larynx causing difficulty breathing and possibly giving rise to bluish discolouration

Symptoms of milk allergy in older children include:

• Rash or hives
• Redness around the mouth or all over the body
• Runny nose, sneezing, itchy watery eyes
• Choking, coughing and wheezing
• Abdominal cramps, vomiting and diarrhoea
• Serious allergic reaction (anaphylaxis) that may be life threatening

Treatment

• Severe milk allergy or anaphylaxis needs to be treated immediately with an injection of adrenaline. In addition, milk, milk products and foods containing even minimal traces of milk proteins must be avoided.
• In mild-to-moderate milk allergy, some cooked foods with traces of milk products may be eaten and not cause a reaction. As it is milk proteins that cause the milk allergy, lactose (milk sugar) is usually well tolerated. However, milk, cheese, yoghurt, cream and ice cream need to be avoided.
• Symptoms of allergy may be treated with antihistamines (e.g. loratadine or cetirizine) These can relieve many of the symptoms of allergy such as hives and itching.