Inflammation of the membrane lining the nose due to an allergic reaction
Allergic rhinitis is a condition in which the membrane lining the nose becomes inflamed. It affects people who experience an allergic reaction after they inhale specific airborne substances (allergens). Allergic rhinitis may occur only in the spring and summer, in which case it is known as seasonal allergic rhinitis or hay fever, or it may be perennial and occur all year round. Allergic rhinitis is more common in people who also have other allergic disorders, such as asthma.
Seasonal allergic rhinitis is usually due to grass, tree, flower, or weed pollens, as well as mould spores. It occurs mostly during the spring and summer when pollen counts are high. The common allergens that provoke perennial allergic rhinitis are house dust mites, animal fur and dander, and feathers.
The symptoms of both forms of allergic rhinitis usually appear soon after contact with the allergen. They include:
Itchy sensation in the nose.
Blocked, runny nose.
Itchy, red, watery eyes.
Some people may develop a headache. If the lining of the nose is severely inflamed, nosebleeds may occur.
Your doctor will probably recognize allergic rhinitis from your symptoms, particularly if you are able to identify the substance that triggers a reaction. A skin prick test may be carried out to identify the allergen that causes the allergic rhinitis. In some cases, the allergen cannot be found.
If you are able to avoid the allergens that affect you, your symptoms will probably subside (see Preventing allergic rhinitis). Many antiallergy drugs are available over the counter or on prescription. For example, allergies can be blocked by nasal sprays that contain corticosteroid drugs (see Corticosteroids for respiratory disease) but may take a few days to work. Nasal sprays containing sodium cromoglicate are an alternative. Nasal sprays containing decongestants can relieve the symptoms but should not be used regularly. Oral antihistamines or an antihistamine nasal spray may relieve inflammation and itching. Eyedrops may help to relieve eye symptoms. Rarely, if symptoms are severe, your doctor may prescribe an oral corticosteroid.
The most specific treatment for allergic rhinitis is immunotherapy, in which you are given gradually increasing doses of allergen with the aim of desensitizing the immune system. This treatment, which typically takes as long as 3–4 years, may be effective for people who are severely affected.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.