Your GP will often be able to diagnose allergic rhinitis from your symptoms and your personal and family medical history.

You will be asked if you have noticed any triggers that seem to cause a reaction, and whether it happens at a particular place or time.

Your GP may examine the inside of your nose to check for nasal polyps. Nasal polyps are fleshy swellings that grow from the lining of your nose or your sinuses (the small cavities inside your nose). They can be caused by the inflammation that occurs as a result of allergic rhinitis

Allergic rhinitis is usually confirmed when medical treatment starts. If you respond well to antihistamines, it is almost certain that your symptoms are caused by an allergy.

Allergy testing

If the exact cause of allergic rhinitis is uncertain, your GP may refer you to a hospital allergy clinic for allergy testing. The two main allergy tests are:

• Skin prick test – where the allergen is placed on your arm and the surface of the skin is pricked with a needle to introduce the allergen to your immune system. If you are allergic to the substance, a small welt (itchy spot) will appear.
• Blood test – to check for the immunoglobulin E (IgE) antibody in your blood. Your immune system produces this antibody in response to a suspected allergen.

Commercial allergy testing kits are not recommended as the testing is often of a lower standard than that provided by the NHS or by accredited private clinics. It is also important that the test results are interpreted by a qualified healthcare professional with detailed knowledge of your symptoms and medical history.

Further tests

In some cases, it may be necessary to have further tests in hospital to check for any complications, such as nasal polyps or sinusitis.

These tests may include:

• a nasal endoscopy – where a thin tube with a light source and video camera at one end (endoscope) is inserted up your nose so your doctor can see the internal part of your nose
• a nasal inspiratory flow test – where a small device placed over your mouth and nose is used to measure the air flow when you inhale through your nose
• a computerised tomography (CT) scan – a type of scan that uses X-rays and a computer to create detailed images of the inside of the body