What is nonallergic rhinitis (NAR) and its common subtypes?

Nonallergic Rhinitis (NAR) and Its Common Subtypes

Nonallergic rhinitis (NAR) is characterized by periodic or perennial symptoms of rhinitis that are not a result of IgE-dependent events, affecting approximately 7% of the U.S. population or ~22 million people. 1, 2

Definition and Prevalence

NAR presents with a minimum of two nasal symptoms including:

• Nasal congestion/obstruction
• Rhinorrhea (anterior and posterior)
• Sneezing
• Nasal itching

Unlike allergic rhinitis, NAR occurs without clinical evidence of endonasal infection and without systemic signs of sensitization to inhalant allergens (negative skin prick tests and/or specific IgE antibodies). 3

Recent data suggests that about 40 million Americans have either pure NAR or mixed rhinitis (both NAR and allergic rhinitis). Studies have found that:

• 23-52% of rhinitis patients have pure NAR
• 34% have mixed rhinitis
• Women appear to be disproportionately affected 1

Common Subtypes of NAR

1. Vasomotor Rhinitis (Nonallergic Rhinopathy)

• Most common subtype, accounting for approximately 65-70% of all NAR cases 1
• Characterized by excessive thin, watery secretions
• Triggered by:
  • Environmental irritants (strong odors, perfumes, tobacco smoke)
  • Changes in temperature, humidity, or barometric pressure
  • Emotional stress
  • Alcohol ingestion
• Pathophysiology involves autonomic imbalance with increased cholinergic tone
• Diagnosis is largely one of exclusion 1

2. Nonallergic Rhinitis with Eosinophilia Syndrome (NARES)

• Accounts for 15-20% of NAR cases 1
• Presents with symptoms similar to vasomotor rhinitis
• Additionally features pruritus of nasal and ocular mucosae and excessive lacrimation
• Diagnosis based on:
  • Clinical syndrome
  • Presence of eosinophils in nasal secretions
  • Absence of evidence for allergy (negative skin tests)
  • Absence of asthma (negative methacholine challenge)
• May occur as isolated syndrome or in conjunction with aspirin sensitivity
• Responds well to treatment with nasal corticosteroids 1

3. Drug-Induced Rhinitis

• Caused by medications including:
  • ACE inhibitors
  • Phosphodiesterase-5 inhibitors
  • Phentolamine
  • α-receptor antagonists
  • Aspirin and NSAIDs
• Rhinitis medicamentosa: rebound nasal congestion following overuse of intranasal α-adrenergic decongestants or cocaine 1, 4

4. Hormonal Rhinitis

• Includes pregnancy rhinitis and menstrual cycle-related rhinitis
• Pregnancy rhinitis features significant nasal congestion
• Typically starts after the second month of pregnancy
• Usually resolves within 2 weeks after delivery 1

5. Gustatory Rhinitis

• Characterized by rhinorrhea occurring after eating, especially spicy foods
• Considered a subtype of vasomotor rhinitis
• Involves autonomic nervous system dysregulation 4, 2

6. Infectious Rhinitis

• May be acute or chronic
• Acute form usually caused by viruses (up to 98% of cases)
• Secondary bacterial infection with sinus involvement may occur as a complication
• Symptoms include nasal congestion, mucopurulent discharge, pain, pressure, headache, olfactory disturbance, postnasal drainage, and cough 1

7. Occupational Rhinitis

• Arises in response to airborne substances in the workplace
• May be mediated by allergic or nonallergic factors 1

8. Atrophic Rhinitis

• Characterized by crusting and foul odor
• Treatment involves continuous nasal hygiene and antibiotics when infection is present 1, 4

Clinical Pearls and Pitfalls

• Diagnostic pitfall: Perennial allergic rhinitis can mimic NAR, so allergy evaluation should be considered even in presumed NAR cases if response to therapy is inadequate 1

• Treatment consideration: Intranasal corticosteroids are the mainstay of treatment for most NAR subtypes, with topical antihistamines and anticholinergics (ipratropium bromide) also showing efficacy for specific symptoms 4

• Emerging concept: Local allergic rhinitis (LAR) or "entopy" should be distinguished from NAR, as it involves allergic reactions confined to the nasal mucosa despite negative systemic allergy tests 3

• Comorbidity awareness: NAR is frequently associated with chronic sinusitis, with 26% of chronic sinusitis patients having NAR in one study 1

• Surgical options: When medical management fails, surgical interventions including inferior turbinate reduction, vidian neurectomy, or posterior nasal neurectomy may be considered 5