An allergy test can establish whether you have an allergy and what you're allergic to. This is key to managing your condition.
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 – a 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 can also help monitor a diagnosed allergy. For example, babies and children with certain food allergies often grow out of them.
A test can let the parents and child know they no longer have an allergy to milk or eggs, for example, so they no longer have to avoid that food.
NHS allergy testing
If you suspect an allergy, see 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.
Your GP may also refer you for testing. Most allergy tests are done in hospital outpatient clinics.
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.
Find your local NHS allergy clinic.
At the allergy clinic, the type of test you're offered will depend on your symptoms.
Possible tests include:
Skin prick test for allergens
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, swollen mark called a wheal will appear.
Blood test for allergens
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 for a skin reaction
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 department in a hospital.
Food challenge for food allergies
A food challenge, also called an oral challenge, is the most accurate way to diagnose a food allergy. During the test, you're given gradually increasing amounts of the food you think you are allergic to, to see how you react. Only one food can be tested at each appointment.
Private allergy testing
If you choose to have private allergy testing, make sure you see a trained specialist.
The Allergy UK helpline team can help you find your nearest NHS allergy clinic or consultant. The helpline number is 01322 619 898, and operates from 9am to 5pm, Monday to Friday.
The helpline team can also give advice on dealing with symptoms and products that may be beneficial for sufferers. They also have access to a panel of health experts for questions of a more complex medical nature.
Find out about treating allergies.