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 [RM]) 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).
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
- 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
- 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
- Exposure to pollutants increase the risk of IgE-mediated allergic disease
- 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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