What is a skin prick test?
A skin prick test is a simple and safe method of testing whether your child has an immediate allergy (IgE mediated) to a specific allergen. It involves pricking the skin with a variety of allergens which with a lancet. This directly introduces the allergen into the skin, a positive response will a cause a small, localised allergic response, in the form of a wheal at the site of the testing.
Skin prick testing is more superior to IgE radioallergosorbent test (RAST) blood test in that it is more sensitive and provides results instantaneously. It is also relatively cheap compared to the RAST testing.
What type of allergens can be tested?
There are many allergens that can be tested including pollen (tree/grass), mould, animal fur/hair, house dust mite, latex, food (all types). If there are no allergen solutions available, prick to prick skin testing with real food can be performed too.
Why is it needed?
Skin prick testing can assist the doctor to make a diagnosis for your child’s symptoms such as chronic cough, sneezing, itchy eyes, wheeze, abdominal pain, eczema or nasal congestion. It is not always simple to find the cause for your child’s symptoms as food allergies in particular can present with many signs and symptoms, affecting different organs of the body such as the skin, chest and gut related symptoms. Food allergy can also affect your child’s mood, concentration and overall wellbeing.
Before the test.
Antihistamines and corticosteroids inhibit the skin reaction. So therefore, it is imperative that all medicines containing antihistamines are stopped for at least three days before the appointment. Systemic steroids should be discontinued the day before the test. Topical steroids should not be applied to the arms.
What does it involve?
The doctor will discuss your child’s allergy history with you, they will explain the procedure to you and your child. The clinician will apply the test allergen on to your child’s skin, normally on the forearm. A blunt lancet will be used to introduce the allergen into the skin. This will allow the test allergen to be in direct contact with the skin. A wheal will usually be formed within 10-15 minutes if you child has immediate allergy to the allergen.
Are there any risks?
The skin prick test is relatively safe. It is exceedingly rare to cause a life-threatening event such as anaphylaxis. Should this happen, your experienced clinician will manage your child’s condition appropriately. The prick can cause a little discomfort and pain, but most children tolerate the procedure. It should not cause bleeding. Your child may experience itching, which tends to settle quite quickly. We can offer an anti-histamine medication if needed.