An allergy test can establish whether you have an allergy and what you're allergic to.
“Knowing what you're allergic to is key to managing your condition,” says Allergy UK’s Lindsey McManus.
“If you have hay fever, you probably don’t need allergy testing as it may be obvious from your symptoms that you’re allergic to pollen. But it’s important to find out the precise cause if your symptoms are more complicated. For example, perennial rhinitis (runny nose all year round) can be triggered by a variety of allergens, such as house dust mites and mould, or a food allergy could be triggered by one of a number of foods in your diet.”
Allergy testing also has a role in monitoring a diagnosed allergy, says Lindsey.
“Babies and children with an allergy, such as certain food allergies, often grow out of them. Regular testing can establish if the allergy has gone. It’s helpful for the parents and the child to know that they no longer have an allergy to milk or eggs, for example, so that they no longer have to avoid that food.”
NHS allergy testing
If you suspect an allergy, the first port of call is your GP. If, after discussing your symptoms, your GP thinks you may have an allergy, they may offer a blood test (formally known as a RAST test) to identify the cause of your allergy. Or they may refer you for testing. Most allergy tests are done in hospital outpatient clinics.
Find your local NHS allergy clinic.
Not every NHS hospital has an allergy clinic, so you may have to wait longer and travel further for testing in some parts of the country.
At the allergy clinic, the type of test you're offered will depend on your symptoms. Possible tests include the following.
Skin prick test
A skin prick test is usually the first test to be done when looking for an allergen. It’s quick, painless and safe, and you get the results within about 20 minutes. Your skin is pricked with a tiny amount of the suspected allergen to see if there's a reaction. If there is, the skin around the prick will very quickly become itchy, and a red wheal will appear.
Blood test
The blood test used to test for allergens is called a specific IgE test (formally known as the RAST test). It's used to measure the number of IgE antibodies in your blood that have been produced by your immune system in response to a suspected allergen.
Patch test
The patch test is used to see if a skin reaction, for example eczema, is caused by contact with a specific chemical or substance. A small amount of the suspect substance or chemical, such as nickel, is added to special metal discs, which are 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.
Food challenge
A food challenge, also called an oral challenge, is the most accurate way to diagnose a food allergy. During the test, you're given the food to which you think you are allergic in gradually increasing amounts to see how you react. Only one food can be tested at each appointment.
Commercial tests
Some commercial allergy testing kits, such as hair analysis tests, kinesiology tests and VEGA tests, are not recommended by doctors because there is little scientific evidence to support them.
Private allergy testing
If you choose to have private allergy testing, it's important to see a reputable, trained specialist. Allergy UK has an online service to help you find an accredited local private allergy specialist.
