When a child has a bad reaction to food, the terms ‘allergy' and ‘intolerance' are often used interchangeably. However these are not the same thing and a better understanding of the differences between the two are required if they are to be treated properly, a paediatric allergy nurse has said.

According to Claire Cullinane of University College Cork (UCC), adverse reactions to food - sometimes referred to as food hypersensitivity - can be divided into allergic reactions and food intolerances.

A food allergy occurs when a particular food elicits an abnormal immunological response in the body. While any food can cause an allergy, a small number are responsible for ‘the large majority of symptoms'. These are milk, eggs, wheat, peanuts, nuts and fish.

On the other hand, food intolerances can be triggered by a number of factors, such as a specific component of the food. An example of this is the flavour enhancer, monosodium glutamate (MSG), which is commonly added to foods such as processed meats, canned vegetables and Chinese food.

Ms Cullinane looked specifically at the issue of cow's milk, as parents often believe their children are allergic or intolerant of this.

She noted that while an intolerance to cow's milk can lead to some nasty symptoms, such as abdominal pain and explosive diarrhoea, as there is no involvement of the immune system, this is not an allergy.

"Cow's milk allergy is not to be confused or incorrectly labeled as an intolerance or vice versa. They are two distinct separate disorders. Both fall under the remit of food hypersensitivity but follow a different treatment pathway," she explained.

She noted that between 5-15% of infants show an intolerance for cow's milk, while actual allergies affect 2-7%.

Ms Cullinane noted that the same trigger food can give rise to different symptoms, resulting in an allergic reaction in one patient and signs of intolerance in another. As a result, it is ‘vital' that those who care for children ‘have a clear understanding of the difference' between both.

She pointed out that it can be difficult to diagnose cow's milk allergy as there is no one symptom that indicates it. Symptoms can include abdominal cramps, diarrhoea, respiratory problems and wheezing.

"The key to diagnosis rests on obtaining a good history backed by appropriate tests," she said.

An intolerance to cow's milk can also be difficult to determine because the reaction may be transient - it may occur today, but not tomorrow and it may depend on the amount of food consumed.

Ms Cullinane added that adverse reactions to food ‘encompass a diverse range of conditions ranging from lactose intolerance to life threatening anaphylaxis'.

"The correct terms of food allergy versus intolerance must be understood and adhered to if we are to diagnose and correctly treat the condition in question."

Ms Cullinane made her comments in WIN (World of Irish Nursing & Midwifery), the Journal of the Irish Nurses and Midwives Organisation.