Allergen challenges paediatric investigations unit
It has been recommended that the child in your care attends an appointment for an allergen challenge.
On this page
This page will give you information about what will happen during the appointment. A few days before the child’s admission please try to discus with them what is going to happen on the day.
What is an allergen challenge?
An allergen challenge involves exposure to something that the child may previously have been allergic to or suspected of being allergic to such as food, medication or latex.
If the child has a reaction to the allergen being challenged, we can quickly give medication and the child will be seen by a doctor. We will also be able to observe the type of reaction and symptoms that the child develops. We will respond and record any reactions for future reference.
Before attending the Paediatric Day Unit
If the child in your care has sickness, diarrhea, a wheeze or a cold, a significant flare-up of hay fever or eczema, the challenge will be unable to go ahead. Please contact the Paediatric Day Unit to cancel the appointment. The contact details are at the end of this leaflet.
Your child must stop taking antihistamines, such as:
Piriton® (Chlorphenamine), Zirtek® (Cetirizine), Clarityn® (Loratadine), Neoclarityn® (Desloratidine), 5 days before coming in to the unit for the food challenge.
What food or other allergen do you need to bring with you?
The allergen to be challenged must be provided by you. For example, peanut butter for a peanut allergy or in the case of an egg allergy, 2 eggs, 1 hard boiled, 1 uncooked. For specific guidance on what to bring with you, please contact the Paediatric Day Unit.
If you do not bring the exact food, including the brand stated, we will not be able to proceed with the challenge.
If the child is on a specific diet, they will need a packed lunch and any snacks they may want.
What medications do you need to bring with you?
Please bring with you, a list of any medications that the child is currently taking (as well as any cough medicines or linctus). The list should include any medication that the child may have stopped taking for the purpose of this challenge.
You will need to bring with you the child’s reliever (blue) inhaler, spacer device and adrenaline pen (e.g. EpiPen®, Emerade™ or Jext® device) if these have been previously prescribed.
In the very unlikely event that the child requires adrenaline and has their own pen device with them, you will be asked (with supervision) to administer this yourself to allow for practice.
What will happen when you arrive?
- The child will be weighed and have their blood pressure, oxygen levels measured and pulse taken.
- Those children (usually age 7 or over) who are able to perform a peak flow may be asked to do so. A peak flow is a quick test that measures the air flow in the lungs.
- Children with eczema will need to show their eczema patches.
How is the allergen given?
The challenge, in the case of food allergies, begins by placing a very small amount of the food in the child’s mouth.
In the case of a latex challenge they will be exposed to a small amount of the latex, for example by touching a latex balloon.
In the case of a medication challenge they will be given very small amounts of the medication, usually by mouth.
If there is no reaction, gradual increasing amounts of the allergen are exposed to your child every 20 minutes. This is until a certain amount of exposure is reached, usually a few teaspoons in the case of food challenges.
The challenge will be paused or stopped at the first sign of an allergic reaction.
Sometimes a food challenge may be inconclusive as young children may refuse to eat the necessary quantity of the food in question. This can be more common in children under 5 years.
If you think it may help, please bring in eating utensils that they are familiar with at home.
If a child only eats a small amount of the food in question without a reaction, we cannot be certain that they are definitely not allergic. To be sure, the child must eat a full portion; usually a few teaspoons.
How long will the allergen challenge take?
The child is normally able to go home after 2 to 4 hours. If they have had a reaction they may need to be observed for longer. A doctor will decide when the child can be safely discharged.
On discharge, you will be given written advice and the result of the challenge. If your child has had an allergic reaction, a follow up appointment is usually made for your child to be seen in an allergy clinic.
Paediatric Day Unit
Gloucestershire Royal Hospital
Tel: 0300 422 8452
Monday to Friday, 7:00am to 7:30pm
If you have any questions please contact the Paediatric allergy team secretary