Visit Your GP
If you think you have an allergy, tell your GP about the symptoms you are having, when they happen, how often they occur and if anything seems to trigger them. Your GP will also want to know if any family members have similar symptoms, or if there is a family history of allergy.
After asking about your allergy history, your GP may carry out tests to identify the allergen that is causing your symptoms, or refer you to a hospital clinic.
Even if you think you know what is causing the allergic reaction, you may need to be tested to determine the exact allergen and get a definite diagnosis. Each allergen is tested individually based on suspected or likely allergens. It is not always possible to identify the allergen causing the problem.
The type of test you are offered will depend on your symptoms, the condition of your skin and any medication you are taking. Possible tests include:
- Skin prick test: This is usually the first test to be done when looking for an allergen. The skin is pricked with a tiny amount of the suspected allergen to see if there is a reaction. If there is, the skin around the prick will very quickly become itchy, red and swollen. Because the skin prick test introduces such a tiny amount of allergen into the skin, the testing is considered very safe and can be used on almost any age group, including babies. However, it may not be suitable if you have a history of severe reaction to an allergen.
- Blood test: This is used to measure the amount of IgE antibodies in your blood that have been produced by your immune system in response to a suspected allergen. The results are given on a scale from zero to six: zero indicates a negative result and six indicates an extremely high sensitivity. Blood tests are particularly useful when you are at risk of an extreme reaction or when a rare allergen is suspected.
- Patch test: This test is used to find an allergen causing eczema (contact dermatitis). A small amount of the suspected allergen is added to special metal discs, which are then taped to your skin for 48 hours and monitored for a reaction. This test is usually carried out at a dermatology (skin) department in a hospital.
The use of commercial allergy testing kits is not recommended. These tests are often of a lower standard than those used in the health services. Also, allergy tests should be interpreted by a qualified professional who has detailed knowledge of your symptoms and medical history. Some allergy testing services sold to the public have no scientific basis and cannot be relied upon.