Children's Community Nursing Service, Richmond
About a skin prick allergy test
We use a skin prick test to help diagnose allergies.
A nurse pricks your child's skin gently through a drop of allergen extract placed on the surface of your child's arm. If your child reacts to the allergen they will have a small, itchy swelling and a reddening of the skin after 10 to 15 minutes.
A drop of allergen is a drop of solution containing a substance you may be allergic to (called an allergen).
Preparing your child for the test
Read the following information carefully before your child’s skin prick test appointment.
If your child attends the appointment feeling unwell with a cough or high temperature, we will not be able to do any testing, as this may not be safe. In this case, we will advise on how to rebook your appointment at a future date.
Antihistamines and travel sickness medicines
- cetirizine
- fexofenadine (Allegra or Allevia)
- loratadine (Clarityn)
To ensure that the test results are accurate, stop giving your child the following short-acting antihistamines at least 2 days before their skin prick test):
- chlorphenamine (Piriton)
- acrivasatine (Benadryl)
- promethazine (Phenergan)
- alimemazine (Vallergan).
Stop giving your child travel sickness medicines 2 days before their skin prick test.
Asthma medicines
If your child currently uses an inhaler to manage their asthma, it is important that they continue to use their preventative (brown) inhalers right up until their skin prick test. This will not affect the results of their skin prick test.
If your child needs to use their blue (salbutamol) inhaler in the 7 days prior to the skin prick test, get in touch with us at least 48 hours before your appointment (see Contacts section).
What to bring on the day
On the day of the appointment, you may need to bring some foods for testing.
Foods you may need to bring with you
If your child is having a test for any of the following foods, you need to bring the relevant food(s) with you.
- Specific fresh fruits
- Specific fresh vegetables
- Meats (only bring cooked meat)
- Fish other than cod, prawn and salmon. You can bring tinned fish in spring water, but remember to bring a tin opener.
- Specific herbs or spices
- Specific seeds
- Any other food not listed below (where we will provide the food at the hospital).
Bring each food in a separate sealed container.
A piece of food the size of a 20p is usually enough for testing.
Foods you do not need to bring with you
If your child is having a test for any of the following food(s), we usually have them available in clinic:
- Peanuts
- Cow’s milk
- Tree nuts (Brazil, hazelnut, almond, pecan, walnut, cashew, pistachio, macadamia)
- Egg
- Soya
- Sesame
- Prawn, cod, salmon, tuna
- Wheat
- Chickpeas
- Pine nut
- Sunflower seed
- Oat, rye, barley.
What happens during the test
A skin prick test appointment usually lasts 30 to 45 minutes.
- A nurse trained in skin prick testing will meet you and your child. Your child can sit on a chair or on your lap if they prefer.
- The nurse will check that your child has not taken antihistamines in the previous 2 to 5 days and discuss with you the foods that we need to test.
- To start the test, the nurse will write an allergen number or name on your child’s arm and put a small drop of the manufactured allergen next to each. Then they will prick each drop with a tiny blade and blot it with a tissue.
- If the test involves fresh food(s) that you have brought with you, the nurse will prick the food with the blade, then prick your child’s skin.
- Your child can play or feed while the nurse waits for the result of the test.
- The test usually takes 15 minutes to work.
What a positive test looks like
- If the skin prick test is positive (confirmation of sensitisation) an itchy bump will develop on your child’s arm.
- The nurse will measure the bump and record the size.
- The bump is likely to fade quickly. We can give your child antihistamine treatment if they need it on the day of the test.
What happens after the test
The nurse will share your results with us, and we will get in touch in the next few weeks to explain the results to you. We usually get in touch with you by phone.
If you have another doctor or dietitian appointment or allergy clinic scheduled within a month's time, we can explain your results to you then.
We will also send a copy of the results and the action plan (if applicable) to you and your GP.
Contact information
Kingston Hospital Paediatric
Outpatients Department
Kingston Hospital
Galsworthy Road
Kingston KT2 7QB
Telephone: