Pertinent Negatives for Allergic Rhinosinusitis
When evaluating a patient for allergic rhinitis, the absence of clear rhinorrhea, pale nasal mucosa, ocular symptoms (red/watery eyes), nasal itching, and sneezing argues against an allergic etiology and suggests nonallergic rhinitis or other diagnoses. 1
Key Symptom Absences That Suggest Non-Allergic Etiology
Absence of Classic Allergic Symptoms
- No nasal itching – This is a hallmark symptom of allergic rhinitis; its absence makes allergy less likely 1, 2
- No sneezing – Paroxysmal sneezing is characteristic of allergic triggers; absence suggests nonallergic rhinitis 1, 3
- No ocular symptoms (red, watery, itchy eyes) – Eye involvement strongly suggests allergic mechanism; absence points away from allergy 1, 2
- No throat itching – Pruritus of the throat is common in allergic rhinitis 2
Physical Examination Findings That Argue Against Allergy
- Absence of pale, edematous nasal mucosa – Allergic rhinitis typically presents with pale, boggy turbinates; erythematous, inflamed turbinates suggest nonallergic rhinitis 1, 2
- Absence of clear rhinorrhea – Allergic rhinitis produces clear, watery discharge; thick, purulent, or mucopurulent discharge suggests bacterial infection or nonallergic rhinitis 1
- Absence of allergic shiners (dark circles under eyes) or nasal crease – These physical signs support allergic etiology when present 1
Negative Testing Results
Immunologic Testing
- Negative skin prick testing for relevant aeroallergens – This essentially rules out IgE-mediated allergic rhinitis and confirms nonallergic rhinitis 1, 4, 2
- Negative serum-specific IgE antibodies – Absence of allergen-specific IgE makes allergic rhinitis unlikely 1, 3
- Poor correlation between allergen exposure and symptoms – Even with positive testing, if symptoms don't correlate with allergen exposure, the patient likely has nonallergic rhinitis 1, 5
Important Clinical Context
A patient with perennial rhinitis and an isolated positive skin test to a seasonal allergen (e.g., ragweed) would not have ragweed-induced allergic rhinitis as the cause of perennial symptoms and most likely has nonallergic rhinitis 1. Up to 54% of the general population tests positive on skin prick tests, so positive tests without clinical correlation are meaningless 5.
Distinguishing Features of Nonallergic Rhinitis
Primary Symptom Pattern
- Predominant nasal congestion and postnasal drainage WITHOUT sneezing or itching – This pattern is classic for nonallergic rhinitis 2, 3
- Symptoms triggered by nonallergic triggers – Weather changes, strong odors, cigarette smoke, barometric pressure changes suggest nonallergic rhinopathy 4, 3
- Associated sinus pressure, ear plugging, muffled sounds – These symptoms are more common in nonallergic rhinitis 2
Response to Treatment
- Poor response to antihistamines – Nonallergic rhinitis responds poorly to antihistamines compared to allergic rhinitis 2, 3
- Better response to intranasal antihistamines than oral antihistamines – This pattern suggests nonallergic rhinitis 2, 3
Critical Pitfalls to Avoid
Do not diagnose allergic rhinitis based on positive allergy testing alone – Testing must correlate with clinical history and symptom timing 1, 5. A pale nasal mucosa and clear rhinorrhea do not always differentiate allergic from nonallergic rhinitis; negative IgE testing is required for definitive differentiation 1.
Absence of eosinophilia on nasal smear does not rule out allergic rhinitis – While nasal eosinophilia can support allergic etiology, its absence is not a reliable pertinent negative 1, 4.
Associated Conditions to Assess
When allergic rhinitis is suspected, document the absence of associated conditions that commonly coexist with allergic disease 1:
- Asthma
- Atopic dermatitis/eczema
- Conjunctivitis
- Sleep-disordered breathing
- Chronic rhinosinusitis
- Otitis media
The absence of these atopic conditions makes isolated allergic rhinitis less likely and should prompt consideration of nonallergic etiologies 1, 6.