Allergic rhinitis is the collection of symptoms involving mucous membranes of nose, eyes, ears, and throat after an exposure to allergens such as pollen, dust, or dander.
- IgE-mediated inflammation of the nasal mucosa following exposure to an extrinsic protein; an immediate symptomatic response is characterized by sneezing, congestion, and rhinorrhea followed by a persistent late phase dominated by congestion and mucosal hyperreactivity.
- Allergic rhinitis can be classified into seasonal or perennial and can be intermittent or persistent.
- Seasonal responses are usually due to outdoor allergens such as tree pollen, flowering shrubs in spring, grasses and flowering plants in summer, and ragweed and mold in fall.
- Perennial responses, or year-round symptoms, are usually associated with indoor allergens like dust mites, mold, and animal dander.
- Occupational allergic rhinitis is caused by allergens at the workplace and can be sporadic or year-round.
- Nonallergic rhinitis (e.g., vasomotor, rhinitis of pregnancy, and rhinitis medicamentosa) can occur.
Chronic nasal obstruction can result in facial deformities, dental malocclusions, and sleep disorders.
Physiologic changes during pregnancy may aggravate all types of rhinitis, frequently in the 2nd trimester.
- Onset usually in first 2 decades, rarely before 6 months of age, with tendency declining with advancing age
- The mean age of onset is 8 to 11 years, and about 80% of cases have established allergic rhinitis by age 20 years.
- ~10–25% of the U.S. adult population and 9–42% of the U.S. pediatric population are affected.
- 44–87% of patients with allergic rhinitis have mixed allergic and nonallergic rhinitis, which is more common than either pure form (1).
- Scandinavian studies have demonstrated cumulative prevalence rate of 14% in men and 15% in women.
Etiology and Pathophysiology
- Aeroallergen-driven mucosal inflammation due to resident and infiltrating inflammatory cells as well as vasoactive and proinflammatory mediators (e.g., cytokines)
- Inhalant allergens:
- Perennial: house dust mites, indoor molds, animal dander, cockroach/insect detritus
- Seasonal: tree, grass, and weed pollens; outdoor molds
- Occupational: latex, plant products (e.g., baking flour), sensitizing chemicals, and certain animals for people working in farms and vet clinics
Complex but strong genetic predilection present (80% have family history of allergic disorders.)
- Family history of atopy, with a greater risk if both parents have atopy
- Higher socioeconomic status
- Tobacco smoke can exacerbate symptoms and increase risk of developing asthma in patients with allergic rhinitis.
- Having other allergies such as asthma
- Unclear evidence regarding risk due to early, repeated exposure to offending allergen and early introduction of solid food
- Pets in house and houses infested with cockroaches can cause perennial allergic rhinitis.
- Male sex
- Primary prevention of atopic disease has not been proven effective by maternal diet or maternal allergen avoidance (2).
- Exclusive breastfeeding to 6 months of age lowers risk of some atopic disorders.
- Symptomatic control by environmental avoidance is the “first-line treatment.”
- HEPA air cleaners and vacuum bags of unclear efficacy
- Close doors and windows during allergy season.
- Use a dehumidifier to reduce indoor humidity.
Commonly Associated Conditions
Other IgE-mediated conditions: asthma, atopic dermatitis, allergic conjunctivitis, food allergy
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