If you think you or your child has a food allergy, make an appointment to visit your GP.
It is likely that your GP will ask you some questions about the pattern of your child’s symptoms, such as:
- How long did it take for the symptoms to start after exposure to the food?
- How long did the symptoms last?
- How severe were the symptoms?
- Was this the first time your child has had these types of symptoms, and if not, how often have symptoms occurred?
- What food was involved and how much of the food did your child eat?
They will also want to know about your child’s medical history, such as:
- Does your child have any other allergies or allergic conditions?
- Is there a history of allergies in your family?
- Was (or is) your child breastfed or bottle-fed?
Your GP may also asses your child’s weight and size to make sure that they are growing at the expected rate.
If your GP suspects that you or your child has a food allergy, you may be referred to an allergy clinic or centre for testing.
If your child had symptoms that came on quickly (an IgE-mediated food allergy) then it is likely that they will be given what is known as a skin-prick test. The doctor may also want to give them a blood test.
If your child’s symptoms developed more slowly (non-IgE-mediated food) then it is likely that they will be put on what is known as a food elimination diet.
More information on these types of test is given below.
Skin-prick testing
During a skin-prick test, drops of diluted foods are placed on the arm. The skin is then pierced, through the drop, using a small needle or pin to introduce the food drops to the system. Itching, redness and swelling would usually indicate a positive reaction. This is usually painless.
A skin-prick test does have a small chance of causing anaphylaxis, so testing should only be carried out where there are facilities available to deal with an anaphylactic reaction. This would usually be at an allergy clinic or centre, hospital or a larger GP surgery.
Blood test
An alternative to a skin-prick test is a blood test to measure the amount of allergic antibodies in the blood.
Food elimination diet
In a food elimination diet, the food suspected of causing the allergic reaction is withdrawn from your or your child’s diet for two to six weeks. The food is then reintroduced into the diet.
If your child’s symptoms go away when the food is withdrawn and then return once the food is introduced then this can normally confirm your child has a food allergy.
You should be given advice from a dietitian, before starting the diet, on issues such as:
- the food and drinks you need to avoid
- how you should interpret food labels
- whether your child needs any alternative sources of nutrition
- how long the diet should last
Do not attempt a food-elimination diet by yourself without discussing it with a qualified health professional.
Alternative tests
There are several shop-bought tests available which claim to detect allergies. They include:
- Vega testing, which claims to be able to detect allergies by measuring changes in your electromagnetic field.
- Kinesiology testing, which claims to be able to detect food allergies by studying your muscle responses.
- Hair analysis, which claims to be able to detect food allergies by taking a sample of your hair and running a series of tests on it.
- Alternative blood tests (leukocytotoxic tests), which claim to detect food allergies by checking for the "swelling of white blood cells".
Many alternative testing kits are expensive, the scientific principles they are alleged to be based on are unproven and independent tests have been found to be unreliable. They should therefore be avoided.
