What are ALLERGIES?
- Allergies (allergic rhinitis, hay fever, seasonal allergies) occur when certain cells in an individual’s body become too sensitive to a foreign particle (allergen) thus causing a variety of general and local symptoms.
- Allergies affect approximately 20% of the general population.
- Allergic rhinitis usually develops in the teenage years or young adulthood and continues for 30 to 40 years before gradually improving.
- Allergic rhinitis is associated with asthma and sinusitis as well as affecting the nasal passages thus increasing the morbidity related to the disease.

- Seasonal allergic rhinitis: Defined by symptoms which occur at the same time every year during exposure to seasonal allergens (ragweed, grasses, and tree pollens).
- Perennial allergic rhinitis: Defined by symptoms lasting more than 2 hours per day and lasting for more than 9 months of the year.  Occurs when allergies develop to house dust mites, indoor molds, animal danders, or when a person acquires sensitivities to multiple seasonal allergens.
- Episodic allergic rhinitis: Defined by symptoms which occur when a person is exposed to allergens not normally present in the environment (pets in someone else’s home).

Causes and symptoms of ALLERGIES
- Allergies occur when an individual becomes hypersensitive to a foreign substance (allergen). The most common allergens are particles in the air, such as pollen, house dust mites, mold or mildew, and animal dander.
- Upon exposure to these allergens, the individual’s immune system overreacts (an IgE mediated response).
- One of the consequences of this immune system response is the release of a number of inflammatory substances (mediators and cytokines).  Histamine is one of these substances.
- Histamine and other mediators cause inflammation of tissues, dilation of blood vessels, and contraction of smooth muscle (i.e muscles in the lungs).
- Symptoms may include itchy or watery eyes, sneezing, runny, stuffy, or itchy nose, temporary loss of smell, headache, fatigue, post nasal drip, dark circles under the eyes, sore throat, insomnia, and irritability.

Treatment of ALLERGIES
- If the cause of the allergic reaction can be discovered, avoidance of that substance is the best treatment. (Examples: seasonal- keep the house and car windows closed, limit time outside. perennial- keep the house well ventilated and dry, keep the kitchen and bathrooms clean, dust often, avoid pets which may cause sensitivity.)
- Patients with severe, persistent allergies who get no relief from environmental modification or over-the-counter medications or those who develop difficulty breathing and asthma-type symptoms should consult a physician. 

- Oral antihistamines may relieve some symptoms including itchy, watery eyes, post nasal drip, runny nose, itchy nose etc. (Specific products may be recommended by a physician or pharmacist.)
- Oral decongestants may relieve sinus congestion thereby helping symptoms like headache and stuffy nose. (Specific products may be recommended by a physician or pharmacist.)
- Topical decongestants applied as nasal sprays may provide relief from a stuffy nose. (Specific products may be recommended by a physician or pharmacist.)
- Oral analgesics may help with sore throat and headache. (Specific products may be recommended by a physician or pharmacist.)
- Options like corticosteroids, anticholinergics, leukotriene modifiers, and immunotherapy are available by prescription only.

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This information is of a general nature and may not apply to your special circumstances. If you have specific questions, please contact your physician or an appropriate health care professional.  These monographs are counseling aids for healthcare professionals only and are not to be used as a reference to diagnose or treat medical conditions.          Copyright 2005 RXinsider LTD