Inhaled, airborne allergens may trigger an immune response in the upper airway in susceptible people. Depending on the allergen, the resulting rhinitis and conjunctivitis may occur seasonally (hay fever) or yearround (perennial allergic rhinitis). The term "hay fever" is a misnomer because hay doesn't cause allergic rhinitis, nor is fever associated with it. Because it affects more than 20 million Americans, allergic rhinitis is the most common atopic allergic reaction. Although the disorder can affect anyone at any age, it's most prevalent in young children and adolescents.
Seasonal allergic rhinitis (commonly called hay fever) is an immunoglobulin (Ig) E-mediated type 1 hypersensitivity response to an environmental antigen (allergen) in a genetically susceptible person. It's usually induced by airborne pollens: in spring by tree pollens (oak, elm, maple, alder, birch, cottonwood); in summer by grass and weed pollens (fescue, bluegrass, English plantain, sheep sorrel); and in fall by weed pollens (ragweed). Occasionally, in summer and fall, it's induced by mold spores.
In perennial allergic rhinitis, inhaled allergens provoke antigen responses that produce signs and symptoms year-round. Major perennial allergens and irritants include house dust and dust mites that feed on the dust, feathers (in pillows and quilts), molds, tobacco smoke, processed materials or industrial chemicals, and animal danders. In many patients, the offending allergens can't be identified. Seasonal pollen allergy may exacerbate symptoms of perennial rhinitis.
Inflammation of the nose, or rhinitis, is the major symptom of AR. Inflammation causes itching , sneezing, runny nose, redness, and tenderness. Sinus swelling can constrict the eustachian tube that connects the inner ear to the throat, causing a congested feeling and "ear popping." The drip of mucus from the sinuses down the back of the throat, combined with increased sensitivity, can also lead to throat irritation and redness. AR usually also causes redness, itching, and watery eyes. Fatigue and headache are also common.
Typically, the diagnosis is made by your child's physician based on a thorough medical history and physical examination. In addition to the above symptoms, your child's physician may find, upon physical examination, dark circles under the eyes, creases under the eyes, and swollen tissue inside the nose.
Appropriate therapy controls signs and symptoms by eliminating the environmental antigen, if possible, and by using drug therapy and immunotherapy in allergic rhinitis.
Antihistamines effectively block histamine effects (such as a runny nose and watery eyes) but commonly produce unpleasant effects, such as sedation, dry mouth, nausea, dizziness, blurred vision, and nervousness. Nonsedating antihistamines, such as terfenadine and astemizole, produce fewer annoying effects and are less likely to cause drowsiness. Newer antihistamines, such as cetirizine and loratadine, have proven effective in clinical trials. Fexofenadine, a derivative of terfenadine, may be effective and carries a lower risk of cardiac arrhythmias than terfenadine.
Taken as prescribed, intranasal corticosteroids may reduce local inflammation with minimal systemic adverse effects. Commonly used drugs are flunisolide and beclomethasone. Usually, these drugs aren't effective for acute exacerbations; nasal decongestants and oral antihistamines may be used instead. Cromolyn sodium may help prevent allergic rhinitis but may take up to 4 weeks to produce a satisfactory effect and must be taken regularly during allergy season. Drug therapy for seasonal allergies requires close dosage regulation.
Long-term management includes immunotherapy or desensitization with injections of allergen extracts administered preseasonally, coseasonally, or perennially. Local nasal immunotherapy is being studied as an alternative route of allergen administration.
Symptoms can sometimes be prevented by avoiding known allergens. During the pollen season, people with hay fever should remain indoors in an air-conditioned atmosphere whenever possible:
For people who are sensitive to certain indoor allergens, dust mite covers for mattresses and pillowcases are recommended, as well as avoiding culprit pets or other triggers.
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