Allergies are common and it is thought that about 1 in 3 of the population will consult a doctor at some time in their life with allergic symptoms. Many cases of rhinitis (tissue inflammation that causes persistent nasal congestion, nose bleeds, nasal itching and sneezing) can be caused by allergies.
This test is simple and quick, giving results within 15-20 minutes, and is carried out by the ENT practice nurse. It is important that you do not take any form of antihistamine or steroid drug for at least 48 hours before the test as these medicines may affect the results. Allergens are introduced into the skin, usually the forearm, in such tiny amounts that testing is quite safe and can be carried out on all age groups, including babies. If you have bad eczema the test can be performed on your back.
The area to be tested is coded with a marker pen for each allergen and a drop of the solution is placed by each code. A standard concentration histamine solution is also applied to serve as a control. The skin is then pricked through the drop using the tip of a single-use sterile lancet. This can feel a little uncomfortable but should not be painful. The nurse will assess the test sites for the presence and size of redness (known as erythema) and lumps (known as wheals) after 15 minutes. The responses are compared to the control histamine solution which should always cause a reaction. The degree of reaction relative to the control indicates whether a certain level of antibodies are present which may be causing your symptoms. The wheals, which feel very much like a reaction to a nettle sting, clear within an hour for most people and any irritation can helped by applying anti-inflammatory steroid cream.