Allergic rhinitis

Allergic rhinitis is an inflammatory response of the nasal mucosa due to exposure to environmental allergens such as house dust, pollen, pet dander, etc. Typical symptoms include sneezing, nasal itching, runny nose, and nasal congestion. The condition may occur seasonally or year-round, depending on the allergen. The pathogenesis involves the release of mediators from mast cells and histamine, leading to inflammatory reactions. Treatment includes avoiding allergens, using antihistamines, topical corticosteroids, leukotriene receptor antagonists, and mast cell stabilizers, depending on disease severity.

Overview

Definition

Allergic rhinitis is an inflammation of the nasal mucosa related to IgE antibodies upon exposure to respiratory allergens, with symptoms like sneezing, nasal itching, runny nose, and nasal congestion.

Epidemiology

Common in individuals with atopy (an exaggerated IgE-mediated immune response, often seen in conditions like atopic dermatitis, asthma, allergic rhinitis, conjunctivitis). It affects 10-30% of the global population, most commonly adolescents, and impacts quality of life.

Divided into two groups based on timing:

• Seasonal: Triggered by pollen, grass, etc., peaking in spring and autumn.
• Year-round: Triggered by house dust, mold, cockroaches, pet dander, textile dust, etc.

Allergens Causing Allergic Rhinitis

Respiratory allergens include house dust, pollen from flowers, grass, trees, mold, feathers, industrial dust, etc. The dose of allergen exposure affects the severity of allergic rhinitis. Tobacco smoke and air pollution are risk factors.

Pathogenesis

Belongs to type I hypersensitivity (Gell and Coombs classification), characterized by IgE antibodies against allergens and the role of mast cells in the nasal mucosa. The disease progresses through stages: sensitization, early phase, and late phase.

• Sensitization Phase: Sensitization to respiratory allergens, forming specific IgE antibodies.
• Early Phase: IgE binds to mast cell surfaces, releasing mediators like histamine, prostaglandins, and leukotrienes, causing symptoms within minutes of allergen exposure.
• Late Phase: Increased migration of eosinophils, basophils, neutrophils, and T-lymphocytes to the nasal mucosa due to chemotactic mediators and cytokines. Symptoms appear 4-6 hours after exposure, peaking at 12-24 hours. Prolonged allergen exposure leads to chronic disease.

Chronic nasal mucosa swelling can obstruct sinuses and Eustachian tubes, leading to secondary infections like sinusitis or otitis media. Nasal obstruction and secretions may disrupt airflow, causing sleep disturbances.

Clinical Symptoms

Common symptoms: persistent sneezing, nasal itching, runny nose, cough, wheezing, nasal congestion, reduced or lost sense of smell, watery eyes, eye itching, fatigue.

Classification (ARIA 2019)

Classified based on severity and duration (Table 1).

Diagnosis

Confirmatory Diagnosis

• Allergy History: Onset, severity, associated symptoms, suspected allergens, family/personal history of atopy (asthma, urticaria, drug/food allergies), living/working environment (dusty, humid, cold).
• Clinical Symptoms: Sneezing, nasal itching, runny nose, cough, wheezing, nasal congestion, reduced sense of smell, watery eyes, eye itching, fatigue.
• Diagnostic Tests:
  • Nasal secretion analysis: Elevated eosinophils.
  • Skin prick tests for suspected allergens.
  • Provocation tests: Reproduce symptoms to confirm respiratory allergens.
  • In vitro tests: Detect specific IgE antibodies for respiratory allergens.

Differential Diagnosis

See Table 2 for conditions to differentiate from allergic rhinitis.

Treatment

Goals

• Improve quality of life.
• Relieve symptoms quickly and prevent recurrence.

Treatment Principles

• Accurately classify disease severity.
• Follow a stepwise treatment approach.
• Avoid allergen exposure (most critical).
• Check for coexisting asthma, especially in severe/persistent cases.
• Use nasal saline irrigation daily to remove allergens.
• Prioritize non-sedating antihistamines.
• Use decongestants and oral corticosteroids only for acute exacerbations, short-term.
• Use nasal corticosteroids in step 2, daily, stopping only after symptoms resolve for at least 1 month.
• Treat coexisting upper/lower respiratory conditions.
• Educate patients: Wear dust masks, learn nasal irrigation, avoid allergens.

Specific Treatments

• Allergen Avoidance
• Medications (Table 3):
  • H1 Antihistamines: Oral (fexofenadine, desloratadine, cetirizine) or topical (azelastine) to reduce histamine-related symptoms (itching, sneezing, congestion).
  • Decongestants: Phenylephrine, pseudoephedrine, oxymetazoline (nasal drops/sprays, not for self-use beyond 3 days).
  • Nasal/Oral Corticosteroids: Fluticasone, mometasone, budesonide (nasal); prednisone, methylprednisolone (oral, short-term for acute cases) to reduce inflammation and swelling.
  • Leukotriene Receptor Antagonists: Montelukast to reduce leukotriene-related symptoms (congestion).
  • Mast Cell Stabilizers: Cromolyn to prevent histamine/leukotriene release.
  • Anticholinergics: Ipratropium (21 mcg/spray, 2 sprays per nostril, 2-3 times daily) to reduce runny nose with minimal systemic effects.
  • Specific Immunotherapy: Effective for seasonal pollen allergies, minimum 3 years. Involves high-dose allergen administration (100x) via subcutaneous injection (SCIT) or sublingual drops/tablets (SLIT) to induce immune tolerance.

Treatment Monitoring

• Reassess after 2-4 weeks.
• If unresponsive: Adjust regimen, escalate step.
• If responsive: Maintain current treatment.

References

1. Ministry of Health, Vietnam. Guidelines for Diagnosis and Treatment of Allergic and Clinical Immunology Diseases, 2014.
2. Ministry of Health, Vietnam. Vietnam National Drug Formulary, Medical Publishing House, 2018.
3. Bousquet J, et al. (2012). Allergic Rhinitis and its Impact on Asthma (ARIA). J Allergy Clin Immunol, 130(5), 1049-62.
4. Orban NT, et al. (2008). Allergic and Non-Allergic Rhinitis. Middleton’s Allergy: Principles and Practice, 7th ed., Mosby, 973-98.
5. Klimek L, et al. (2019). ARIA Guideline 2019: Treatment of Allergic Rhinitis in the German Health System. Allergo Journal International, 28, 255-276.
6. DeShazo RD, et al. (2018). Allergic Rhinitis: Clinical Manifestations, Epidemiology, and Diagnosis. UpToDate, updated Jan 25, 2018.
7. Sur DK, Plesa ML. (2015). Treatment of Allergic Rhinitis. American Family Physician, 92(11), 985-992.
8. MSD Manuals. Allergic Rhinitis. Retrieved Aug 28, 2024, from https://www.msdmanuals.com.
9. Butler J. (2022). What Is Allergic Rhinitis and Why Is It Called Hay Fever? NasoNeb®. https://www.nasoneb.com.
10. Cleveland Clinic. Allergic Rhinitis (Hay Fever). Retrieved Aug 28, 2024, from https://my.clevelandclinic.org.