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Overview

Allergic rhinitis is an inflammation of the nasal mucosa, the membrane or tissue that lines the inside of the nose. Most of us know it simply as hay fever. It is a very common condition, affecting millions of Canadians. It can occur at any time of the year but is more common in the spring and fall.

Causes

All allergies are caused by an oversensitive immune system. Hay fever is no different. In this case the trigger is pollen from plants, flowers, grass, and weeds. Just one ragweed plant can generate one million grains of pollen and it takes fewer than a thousand to trigger an allergic reaction.

When pollen is inhaled the body produces antibodies such as histamine that are stored in mast cells in the nose and eyes. These antibodies are designed to fight what the body perceives as an invader. Allergy sufferers have higher levels of these chemicals than most people so when they breathe in pollen more histamine is released into their bodies, triggering a variety of telltale symptoms.

Symptoms

Many people think they have a cold or virus when they began suffering from allergies. The reason: Many of the signs of a cold -- watery eyes, runny nose, congestion, itchy throat -- are also symptoms of allergies. So how do you know the difference? The most prominent sign of allergy is itchiness in the eyes, nose,throat , and even the ears. Colds don't do that. Another sure-fire sign is the length of time symptoms persist. Nasal congestion that lasts more than five days is unlikely to be the result of a cold. Doctors can determine if you have an allergy by examining the inside of the nose. With allergies the mucus membrane inside the nose is pale but when there is an infection it is usually red.

Treatment

There is relief available for people with allergies.Treatment rangesfrom targeted therapies such as "nasal puffers" and eye drops to more generalized therapies such as antihistamines. Your doctor may recommendyou seean allergist to identifyyour allergy triggers which you should then try to avoid.The allergist will also be able to diagnose whether your symptoms require more intensive medical intervention.

If the season is long and you don't respond to medication you may need allergy injections which block the symptoms by building up antibodies.Called immunotherapy, the shots involve the injection of tiny amounts of allergenic extracts usually over a period of three to five years. By gradually increasing the amount of extract, tolerance to the troublesome allergen will increase and symptoms will usually be relieved.

Prevention

The best way to prevent hay fever is to avoid the pollen that triggers an allergic reaction:

• Keep windows closed at night to prevent pollen from drifting into your home.
• Keep your early morning outdoor activities to a minimum. That's when trees and plants usually emit pollen.
• Close your car windows.
• Stay indoors when pollen counts are high and on windy days when pollen is being blown around.
• Be sure to take medications prescribed by your allergist.
• Don't hang bed sheets or clothing out to dry. They may collect pollen.

Reviewed by Dr. Mike Evans, M.D.
Updated February 28, 2008