Harvey's Garden

Allergic rhinitis

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aliases

4 min read

Epidemiology & Risk Factors

  • Prevalence: 10–30% of adults and children; peak incidence in adolescence.
  • Strong personal or family hx of atopy (atopic triad: allergic rhinitis, atopic dermatitis, asthma).
  • Common aeroallergens:
    • Seasonal: Tree, grass, and weed pollens.
    • Perennial: House dust mites, pet dander, cockroaches, mold spores.

Clinical Features

  • History:
    • Paroxysmal sneezing, pruritus (nose, eyes, palate), clear watery rhinorrhea, and nasal congestion.
    • Symptoms worsen upon allergen exposure or seasonally.
  • Physical Exam:
    • Nasal mucosa: Pale, boggy, bluish, or edematous nasal turbinates with thin, watery secretions.
    • Eyes: Bilateral conjunctival injection, chemosis, tearing.
    • Dermatologic / Craniofacial Signs:
      • “Allergic shiners”: Infraorbital dark circles due to venous stasis.
      • “Allergic salute”: Transverse nasal crease across the bridge of the nose from chronic upward rubbing.
      • “Dennie-Morgan lines”: Accentuated skin folds beneath the lower eyelids.
      • “Cobblestoning”: Hyperplastic lymphoid follicles on the posterior pharyngeal wall from chronic postnasal drip.

Diagnosis

  • Initial/Screening: Clinical diagnosis based on characteristic hx and PE findings; routine testing is unnecessary.
  • Confirmatory/Gold Standard: Percutaneous skin-prick testing (detects specific allergen-induced IgE; reserved for refractory cases or when planning immunotherapy).
  • Key Labs:
    • Serum allergen-specific IgE (RAST/ImmunoCAP): Indicated if skin-prick testing is contraindicated (e.g., severe dermatographism, extensive eczema, inability to withdraw antihistamines).
  • Imaging: Not routinely indicated; non-contrast sinus CT only if chronic rhinosinusitis or anatomical obstruction (e.g., neoplasm, deviated septum) is suspected.
  • Biopsy: Not indicated.

Differential Diagnostics

  • Nonallergic (Vasomotor) Rhinitis:
    • Diff by later onset (>20 yo), predominance of nasal congestion/rhinorrhea without pruritus or sneezing, triggers include weather/temperature shifts, spicy foods, and irritants/odors; nasal mucosa typically erythematous rather than pale/boggy; (-) allergy testing.
  • Rhinitis Medicamentosa:
    • Diff by hx of topical nasal decongestant use (e.g., oxymetazoline, phenylephrine) for >3–5 consecutive days; marked rebound congestion upon withdrawal; beefy-red, swollen mucosa.
  • Infectious Rhinitis (Viral URI):
    • Diff by acute onset, transient course (<7–10 days), associated systemic features (malaise, low-grade fever, sore throat), and erythematous (not pale) nasal mucosa.
  • Nasal Polyposis:
    • Diff by direct visualization of smooth, gray, avascular, tear-shaped masses in the middle meatus; often associated with Aspirin-Exacerbated Respiratory Disease (AERD) or cystic fibrosis in pediatrics.
  • CSF Rhinorrhea:
    • Diff by clear, persistent, unilateral rhinorrhea that increases with leaning forward or Valsalva, presence of a metallic or salty taste, and positive test for beta-2 transferrin; often follows head trauma or skull base surgery.

Management

  • Environmental & General Measures:
    • Allergen avoidance (HEPA air filters, impermeable mattress/pillow encasings, pet exclusion).
    • Isotonic nasal saline irrigation (flushes allergens and thins secretions).
  • First-line Therapy:
    • Intranasal Corticosteroids (INCS) (e.g., fluticasone, budesonide, mometasone):
      • Most effective single agent for symptom relief (improves congestion, pruritus, rhinorrhea, and sneezing).
      • Recommended initial monotherapy for moderate-to-severe or persistent symptoms.
    • Oral 2nd-generation antihistamines (e.g., cetirizine, loratadine, fexofenadine):
      • Preferred for mild or intermittent symptoms; poor efficacy for congestion.
      • Favored over 1st-generation antihistamines (diphenhydramine, chlorpheniramine) due to lack of sedation and anticholinergic effects.
  • Second-line / Combination Therapy:
    • Combination INCS + Intranasal Antihistamine (e.g., fluticasone + azelastine): Superior to monotherapy for severe symptoms refractory to single-agent INCS.
    • Intranasal antihistamines (e.g., azelastine, olopatadine): Rapid onset, effective for nasal congestion and postnasal drip.
    • Leukotriene receptor antagonists (LTRA) (e.g., montelukast): Useful adjunct in pts with concurrent asthma; black box warning for neuropsychiatric events.
    • Intranasal cromolyn: Mast cell stabilizer; safe in pregnancy and pediatrics, but requires frequent dosing (tid–qid) and pre-exposure administration.
    • Oral/Topical Decongestants (e.g., pseudoephedrine, oxymetazoline): Limit topical use to <3–5 days to prevent rebound congestion (rhinitis medicamentosa).
  • Refractory Disease:
    • Allergen-specific Immunotherapy (AIT):
      • Subcutaneous (SCIT) or sublingual (SLIT).
      • Only disease-modifying treatment; reduces risk of future asthma development; indicated for severe symptoms refractory to pharmacotherapy or intolerable medication side effects.

Complications

  • Secondary bacterial rhinosinusitis (due to ostiomeatal complex obstruction).
  • Otitis media with effusion (OME) and Eustachian tube dysfunction.
  • Exacerbation of comorbid asthma.
  • Chronic mouth breathing leading to craniofacial abnormalities (e.g., high-arched palate, dental malocclusion) in children.
  • Obstructive sleep apnea (OSA), sleep fragmentation, and daytime somnolence.
  • Rhinitis medicamentosa secondary to improper over-the-counter decongestant use.

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