Respiratory Allergies (Allergic Rhinitis)

Overview

Allergic rhinitis, commonly called “hay fever,” is an inflammatory condition of the nasal passages triggered by an immune‑mediated reaction to airborne allergens such as pollen, mold spores, animal dander, or dust‑mite proteins. The immune system mistakenly identifies these harmless particles as threats, releasing histamine and other chemicals that cause classic nasal symptoms.

Who it affects: It can develop at any age, but:

• Children and adolescents have the highest incidence, with up to 40 % affected in some school‑based studies.
• Adult prevalence ranges from 10–30 % worldwide, with a slight female predominance after puberty.

Global prevalence: According to the World Health Organization (WHO) and the Global Allergy and Asthma European Network (GA²LEN), more than 400 million people worldwide have allergic rhinitis, making it one of the most common chronic respiratory conditions.¹

Symptoms

Symptoms may be seasonal (triggered by specific pollinating plants) or perennial (year‑round exposure to indoor allergens). They often appear within minutes of exposure and can vary in intensity.

Upper‑respiratory symptoms

• Sneezing: Repetitive, often in rapid bursts.
• Nasal congestion: A feeling of “stuffiness” caused by swollen nasal tissues.
• Rhinorrhea: Clear, watery nasal discharge that may become thicker later in the day.
• Itchy nose, palate, or throat: A tingling sensation that triggers throat clearing.
• Post‑nasal drip: Mucus draining down the back of the throat, leading to cough or throat irritation.

Ocular and other symptoms

• Itchy, red, watery eyes (allergic conjunctivitis).
• Ear fullness or mild hearing loss due to eustachian‑tube dysfunction.
• Fatigue or reduced concentration: Sleep disruption from nasal obstruction.

Severity classification (per ARIA guidelines)

• Intermittent: Symptoms ≤4 days/month.
• Persistent: Symptoms >4 days/month.
• Mild: No sleep disturbance and no impairment of daily activities.
• Moderate‑to‑severe: Sleep disturbance, reduced work/school performance, or troublesome symptoms despite OTC treatment.

Causes and Risk Factors

Immunologic mechanism

Allergic rhinitis is an IgE‑mediated Type I hypersensitivity reaction:

1. First exposure → allergen‑specific IgE production by B‑cells (sensitization).
2. IgE binds to mast cells in the nasal mucosa.
3. Re‑exposure → allergen cross‑links IgE → mast‑cell degranulation.
4. Release of histamine, leukotrienes, prostaglandins → vasodilation, mucus production, nerve irritation.

Common allergens

• Pollen: Tree (spring), grass (late spring‑summer), weed (fall).
• Dust mites: Dermatophagoides farinae and D. pteronyssinus.
• Animal dander: Cat, dog, rodent proteins.
• Mold spores: Indoor (e.g., Aspergillus) and outdoor (e.g., ragweed).
• Cockroach debris: Particularly prevalent in densely populated urban housing.

Risk factors

• Positive family history of atopy (asthma, eczema, allergic rhinitis).
• Early‑life exposure to indoor allergens (e.g., sleeping with a pet).
• Living in high‑pollen or high‑pollution areas.
• Occupational exposure to irritants (e.g., grain workers, farmers).
• Smoking or second‑hand smoke, which impairs mucociliary clearance.
• Vitamin D deficiency – emerging evidence links low levels with heightened atopic response.²

Diagnosis

Diagnosis is clinical, supported by history, physical exam, and targeted testing when needed.

History & Physical Examination

• Timing of symptoms (seasonal vs. perennial).
• Trigger identification (pollen calendars, pet exposure, home environment).
• Examination of nasal mucosa – pale, edematous turbinates; clear discharge.
• Eye exam for allergic conjunctivitis.

Allergy testing

1. Skin‑prick test (SPT): Small drops of standardized allergen extracts are placed on the forearm; a positive wheal (≥3 mm) within 15 minutes confirms sensitization. Highly sensitive and results are available within an hour.
2. Serum specific IgE (sIgE) testing: Blood draw analyzed by ImmunoCAP or similar platforms. Useful when skin testing is contraindicated (e.g., severe skin disease, antihistamine use that cannot be stopped).
3. Component‑resolved diagnostics: Identifies specific allergen proteins, aiding in predicting cross‑reactivity and severity.

Additional investigations (when indicated)

• Acoustic rhinometry or rhinomanometry – objective measurement of nasal airflow when surgery is contemplated.
• CT scan of sinuses – to rule out chronic sinusitis if facial pain or persistent discharge is present.

Treatment Options

Treatment follows a stepwise approach (ARIA guidelines) that combines pharmacotherapy, allergen avoidance, and immunotherapy for long‑term control.

1. Pharmacologic therapy

2. Allergen‑specific immunotherapy (AIT)

• Subcutaneous immunotherapy (SCIT): Weekly injections building up to a maintenance dose over 3–5 months, then monthly maintenance for 3–5 years. Demonstrated to reduce symptom scores by 30–40 % and may prevent new sensitizations.³
• Sublingual immunotherapy (SLIT): Daily tablets or drops taken at home. Comparable efficacy for grass‑pollen and dust‑mite allergy with a better safety profile.

3. Procedural interventions (reserved for refractory cases)

• Radiofrequency turbinate reduction: Shrinks hypertrophic inferior turbinates, improving airflow.
• Septoplasty: Corrects structural deviation that worsens obstruction.
• Endoscopic sinus surgery: Indicated when chronic sinusitis coexists and does not respond to medical therapy.

4. Lifestyle & environmental control

Effective non‑pharmacologic measures often amplify drug efficacy and may allow dose reduction.

Living with Respiratory Allergies (Allergic Rhinitis)

• Daily nasal rinse: Use a neti pot or squeeze bottle with isotonic saline (1 L of boiled, cooled water + 1/4 tsp salt) once or twice a day during peak pollen season.
• Allergen‑proof bedding: Encase pillows and mattresses in allergen‑impermeable covers; wash bedding weekly in hot water (>130 °F).
• Humidify wisely: Keep indoor humidity between 30–50 % to limit dust‑mite growth; use a dehumidifier in damp basements.
• Pet management: Keep animals out of bedrooms, bathe them weekly, and vacuum with a HEPA filter.
• Air filtration: Portable HEPA air cleaners in the bedroom and living room can reduce indoor pollen and mold spores.
• Medication schedule: Take intranasal steroids regularly (not only when symptoms flare) for optimal control; set a daily alarm if needed.
• Monitor pollen counts: Use local forecasts or apps; limit outdoor activity on days with high counts, especially between 5–10 a.m. when pollen concentration peaks.
• Exercise: Indoor workouts during high‑pollen days; wear a pollen mask if exercising outdoors.
• Travel tips: Pack a “travel allergy kit” (nasal spray, antihistamine, saline sachets) and research allergen seasons at the destination.

Prevention

While you cannot eliminate genetic predisposition, you can substantially reduce exposure and subsequent sensitization:

1. Early environmental control: Keep infants' rooms dust‑mite free; avoid indoor smoking.
2. Probiotic and breastfeeding support: Some studies suggest exclusive breastfeeding for ≥4 months may lower risk of allergic rhinitis in childhood.⁴
3. Vaccinations: Annual influenza vaccine and COVID‑19 vaccination reduce the likelihood of viral infections that can exacerbate allergic rhinitis.
4. Avoid tobacco smoke & pollutants: Air quality indexes (AQI) above 100 correlate with higher symptom scores.
5. Regular cleaning: Vacuum with HEPA, mop floors, and wash curtains to remove settled pollen.

Complications

If left untreated or poorly controlled, allergic rhinitis can lead to:

• Sinusitis: Chronic inflammation predisposes to bacterial overgrowth; up to 30 % of chronic sinusitis patients have coexisting allergic rhinitis.⁵
• Middle‑ear effusion: Eustachian‑tube dysfunction can cause conductive hearing loss, especially in children.
• Sleep‑related disorders: Nasal obstruction contributes to obstructive sleep apnea and daytime fatigue.
• Asthma exacerbation: Upper‑airway inflammation can extend to lower airways; allergic rhinitis is present in >80 % of asthma patients.
• Reduced quality of life: Impaired school or work performance, decreased physical activity, and heightened health‑care costs.

When to Seek Emergency Care

References

1. World Health Organization. Global report on allergy and asthma. WHO, 2022.
2. Han Y, Kim H. Vitamin D deficiency and allergic disease in children. J Allergy Clin Immunol. 2021;147(3):e59–e60.
3. Scadding GK. Allergen immunotherapy: past, present and future. Allergy. 2020;75(12):2858‑2868.
4. Boyle RJ, et al. Breastfeeding and the development of allergic disease. Pediatrics. 2022;149(2):e2021051234.
5. Fokkens WJ, et al. European position paper on rhinosinusitis and nasal polyps 2022. Rhinology. 2022;60(1):1‑112.