Diagnosing allergies relies on a careful medical history, examination and special allergy tests. So how can you tell is it an allergy?
What is food allergy?
It involves the body’s immune system producing an abnormal reaction to a food, which is not in itself harmful.
A food intolerance is a reaction to food that does not involve the immune system.
What’s the difference?
Food allergy can cause a severe reaction (anaphylaxis) so it is really important to find a trained clinician who can accurately diagnose one from the other.
Food allergy occurs in young children at a rate of between 5-10%.
Food allergy is classified as:
immediate – within minutes to two hours of eating (IgE-mediated)
or, delayed up to 48 hours after eating (non-IgE-mediated reactions)
What are the symptoms of food allergy?
Food allergy can cause symptoms involving some or all of the following:
- the skin (itch, redness, hives, eczema, swelling around the lips, face and eye)
- gut (nausea, vomiting, diarrhoea, colicky pain, reflux, constipation)
- airway (cough, wheezing, shortness of breath, chest tightness)
- circulation (sudden paleness; sudden drop in blood pressure and/or collapse)
Food intolerance usually causes gut symptoms.
What foods are involved?
Cow’s milk, hen’s egg, wheat, soya, peanut, tree nut, sesame, fish and kiwi fruit are responsible for the majority of food-induced allergic reactions in children.
In general, children with milk, egg or wheat allergies are likely to outgrow them during childhood, while those with nut, fish or shellfish allergies are likely to remain allergic into adulthood.
How do I know that my child has a food allergy?
Usually, they display certain signs that are consistent with an allergic reaction after contact (usually eating) with a particular food or substance (allergen).
To test or not to test?
There is no stand alone “test”, despite what you might read and hear. The only true test of food allergy is when every time a food is eaten there is a reproducible reaction that occurs within a certain amount of time. Given that some food allergies can cause a severe reaction (anaphylaxis), this is not something that’s recommended.
The starting point for any health care professional assessing your child is an allergy-focused history. Then and only then may skin prick testing or specific IgE blood testing be considered as they are only one small part of the diagnosis. Food intolerance is best diagnosed by a registered dietitian.
Important questions to ask any person offering allergy or intolerance testing are:
- What is the evidence that this test has a valid role for diagnosing food allergy or intolerance that my child might have?
- What does the result of this test mean – is my child sensitised, allergic or intolerant?
- Applied kinesiology, hair analysis, or IgG blood testing should never be used to diagnose or manage food allergy or intolerance. There simply is not enough robust scientific reliable evidence to support their use.
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