Food allergy usually presents at the age of weaning. Therefore, allergy testing is performed on children as young as 5-6 months old.

Allergy can present prior to this age in the form of eczema or gastrointestinal symptoms such as colic, reflux, constipation and feeding difficulties. Therefore, a comprehensive allergy consultation in very young babies with these symptoms is appropriate and testing may then be deferred until 6 months old.

The allergy consultation is approximately 45 mins. The history is the most important part of the consultation as this identifies the likelihood of allergy and guides testing. The actual allergy testing takes 15-20 mins. Following testing, results are explained and a management plan provided.

Allergy testing is performed by skin prick testing. The allergens used are extracts. A small drop of allergen is placed on the forearm. Small lancets are then used to introduce the allergen to the skin. This is done by just touching the surface of the skin. There is no bleeding. Children, and particularly babies, usually tolerate it well and it is not painful. However, toddlers may become upset by being held still for the testing. Occasionally, blood testing is advised but this is not routine and only in certain cases.

Skin prick testing is very safe with a low risk of a reaction. Occasionally, it will be advised to have blood testing done rather than skin testing, in cases where there is a greater risk of a reaction, such as current asthma flaring or a history of very severe anaphylaxis/severe asthma. It is not expected that any adverse reaction should occur as the allergen is an extract rather than fresh food and it is only tested on the skin.

If you have had an allergic reaction in the week before, please take your anti-histamine if necessary. Anti-histamines can interfere with test results and so please contact the clinic to see if your appointment needs to be re-scheduled.

It is best to defer testing for 2-3 weeks after a severe reaction. However, if you are very worried about the reaction and would prefer to be seen sooner, it is fine to make an appointment before this time.

The allergens that are tested are guided by the history of symptoms. Best practice advises against testing unless there is a definite history of allergic symptoms. The only exception is in small children who are at risk of allergy; in these children, testing is carried out on foods that have not been eaten before in order to decide if it is safe to introduce these into the diet. Only certain foods are likely to cause allergy. The allergens to be tested will be discussed with you during the allergy consultation.

There is a very small chance of a sibling also having a peanut allergy. If you are worried about this, allergy testing can be performed to identify if a sibling is sensitized to peanuts before introduction into the diet.

There are no scientifically validated tests for food intolerance. An allergy consultation can be helpful to differentiate food allergy from food intolerance. Negative allergy testing can be useful to confirm a particular food is not causing allergy and can safely remain in the diet. Food intolerance is managed by eliminating the suspected food from the diet and then, re-introducing with close monitoring of symptoms during this time.

It is not advised to undergo testing unless there are definite symptoms causing trouble which require further evaluation or if there is a potential risk of allergy.