Allergic Rhinitis Clinical Overview
I. The "On-Call" Snapshot
Clinical Significance in Malaysia: This is one of the most common reasons patients present to primary care with chronic cough, blocked nose, and what they call "resdung." It significantly impacts quality of life and is a major comorbidity for asthma.
High-Yield Definition: Allergic Rhinitis (AR) is an IgE-mediated inflammation of the nasal mucosa secondary to allergen exposure.
Clinical One-Liner: Basically, it's an over-reactive nose causing cold-like symptoms—runny nose, sneezing, itching, and congestion—but it's triggered by allergens, not a virus.
II. Etiology & Risk Factors
Etiology: An IgE-mediated, Type 1 hypersensitivity reaction to airborne allergens.
Risk Factors:
Non-modifiable:
Strong family history of atopy (asthma, eczema, AR).
Male sex (in childhood).
Modifiable/Environmental (Key Malaysian Triggers):
Perennial (Year-round): House dust mites (
Dermatophagoides pteronyssinus), cockroach allergens, animal dander (especially cats), mould spores.Seasonal/Episodic: Pollens (grass, oil palm), haze.
III. Quick Pathophysiology
It's a two-phase reaction.
Early Phase (minutes): An allergen (e.g., dust mite particle) enters the nose of a sensitised person. It cross-links IgE antibodies on mast cells. This causes mast cell degranulation, releasing histamine and other mediators. This histamine release causes the immediate symptoms: vasodilation (congestion), increased vascular permeability (rhinorrhea), and sensory nerve stimulation (itching, sneezing).
Late Phase (4-6 hours): Inflammatory cells like eosinophils, basophils, and T-cells are recruited to the nasal mucosa. This causes a more sustained inflammatory response, leading to chronic congestion, post-nasal drip, and nasal hyperreactivity. This is why a single exposure can cause symptoms for hours or days.
IV. Clinical Assessment
Red Flags & Immediate Actions:
Signs of Anaphylaxis (rare with inhaled allergens alone, but possible): Stridor, wheezing, hypotension, angioedema. → Action: Stop exposure, call for help (alert your senior/MO), administer IM Adrenaline 0.5mg, secure airway, and start ABCDE management.
Severe, uncontrolled asthma exacerbation: → Action: Treat the asthma aggressively as per guidelines. Uncontrolled rhinitis makes asthma control impossible.
History:
Common (>50%): Watery anterior rhinorrhea, paroxysmal sneezing (multiple times in a row), nasal itching, nasal congestion.
Less Common (10-50%): Itchy palate/throat/ears, post-nasal drip, cough, allergic conjunctivitis (itchy, watery, red eyes), hyposmia (reduced sense of smell).
Pertinent Negatives to rule out differentials:
Fever, purulent discharge, facial pain (suggests sinusitis).
Unilateral symptoms, epistaxis (warrants ENT referral to rule out pathology).
Physical Examination:
General: Mouth breathing, fatigue.
Eyes: "Allergic shiners" (infraorbital venous congestion from nasal obstruction), Dennie-Morgan lines (creases below the lower eyelids), conjunctival injection.
Nose: "Allergic salute" (transverse nasal crease from upward rubbing of the nose, common in children). On anterior rhinoscopy, look for pale, bluish, boggy/edematous inferior turbinates and clear, watery secretions.
Throat: "Cobblestone" appearance of the posterior pharynx from lymphoid hyperplasia.
Clinical Pearl: Don't just focus on the nose. Always ask about eye symptoms and asthma control. The concept is "one airway, one disease." Managing the nose helps the lungs.
V. Diagnostic Workflow
This is almost always a clinical diagnosis. Don't order tests without thinking.
Differential Diagnosis:
Viral Rhinitis (Common Cold):
Points For: Similar initial symptoms (rhinorrhea, congestion).
Points Against: Usually self-limiting (<10 days), associated with fever, sore throat, myalgia. Nasal discharge may become mucopurulent. Turbinates are typically erythematous, not pale/boggy.
How to Differentiate: Clinical history and time course.
Non-allergic Rhinitis (e.g., Vasomotor):
Points For: Chronic nasal congestion and rhinorrhea.
Points Against: Prominent triggers are non-allergic (e.g., changes in temperature, strong odors, spicy food). Itching and sneezing are less prominent. Onset is typically in adulthood.
How to Differentiate: History of triggers and absence of other atopic features.
Acute/Chronic Rhinosinusitis:
Points For: Nasal congestion.
Points Against: Presence of purulent discharge, facial pain/pressure, fever, and hyposmia for >10 days.
How to Differentiate: Clinical features. CT scan is not for primary care diagnosis unless complications are suspected.
Investigations Plan:
Bedside / Initial: None required for a typical presentation.
First-Line Labs & Imaging: Generally not indicated. An FBC might show eosinophilia, but this is non-specific.
Confirmatory / For Specialist Clinic:
Skin Prick Test (SPT): The gold standard to identify specific allergens. Done by Allergy/Immunology or ENT.
Serum specific IgE (RAST): An alternative to SPT if there are extensive skin conditions or the patient cannot stop taking antihistamines. It is more expensive.
VI. Staging & Severity Assessment
We use the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines. It's simple and dictates management.
Classify by Duration:
Intermittent: Symptoms < 4 days per week OR < 4 consecutive weeks.
Persistent: Symptoms > 4 days per week AND > 4 consecutive weeks.
Classify by Severity:
Mild: None of the following are present:
Sleep disturbance
Impairment of daily activities, leisure, or sport
Impairment of school or work performance
Troublesome symptoms
Moderate-Severe: One or more of the above items are present.
This gives you four categories: Mild Intermittent, Mild Persistent, Moderate-Severe Intermittent, and Moderate-Severe Persistent.
VII. Management Plan
Immediate Stabilisation (ABCDE Plan): Only for the rare cases with anaphylaxis or severe asthma as mentioned in the red flags. Standard resuscitation protocols apply.
Definitive Treatment (The Ward Round / Clinic Plan): This is a stepwise approach based on the ARIA classification.
Allergen Avoidance & Patient Education (For ALL patients):
Counsel on avoiding known triggers: dust mite-proof bedding, regular vacuuming, removing carpets/stuffed toys, keeping pets out of the bedroom.
Crucially, teach the correct nasal spray technique: Aim slightly outwards and upwards, away from the nasal septum, and sniff gently. Poor technique is a major reason for treatment failure.
Mild Intermittent AR:
First-Line: Second-generation oral antihistamine (as needed).
Loratadine 10mg OD or Cetirizine 10mg OD.
Avoid first-generation antihistamines like Chlorpheniramine (Piriton) due to sedation.
Moderate-Severe Intermittent OR Mild Persistent AR:
First-Line: Intranasal Corticosteroid (INS) spray daily. This is the single most effective treatment.
Mometasone furoate 2 sprays/nostril OD.
Fluticasone furoate 2 sprays/nostril OD.
Can add an oral antihistamine if symptoms are not fully controlled.
Moderate-Severe Persistent AR:
First-Line: Intranasal Corticosteroid (INS) spray daily is mandatory.
Step-Up Options:
Add an oral antihistamine.
Add a leukotriene receptor antagonist (LTRA), especially if there is co-existing asthma.
Montelukast 10mg ON.
Consider a short course of oral decongestants (e.g., Pseudoephedrine) for severe congestion, but for max 3-5 days to avoid rhinitis medicamentosa.
If symptoms remain uncontrolled, refer to ENT/Allergy for consideration of immunotherapy.
Long-Term & Discharge Plan:
Emphasize that treatment (especially INS) needs to be regular, not just "as needed." It takes days to weeks to see the full effect.
Plan for review in 2-4 weeks to assess response and step up or step down therapy.
Ensure they have a prescription with enough refills.
VIII. Complications
Immediate: Impaired quality of life, sleep disturbance, poor work/school performance.
Short-Term: Acute sinusitis (blockage of sinus ostia), acute otitis media (Eustachian tube dysfunction).
Long-Term: Chronic rhinosinusitis, development of nasal polyps, worsening of asthma control.
IX. Prognosis
Excellent for symptom control with appropriate, consistent treatment.
It is often a lifelong condition with waxing and waning severity.
Top 3 Prognostic Factors (for control):
Patient adherence to medication (especially INS).
Effectiveness of allergen avoidance.
Presence and control of comorbidities (especially asthma).
X. How to Present to Your Senior
"Dr, for review please. This is [Patient Name], a [Age]-year-old [Gender], with a history of asthma, presenting with a 2-month history of daily blocked nose, sneezing, and watery rhinorrhea. These symptoms are disturbing his sleep and work. On examination, his turbinates are pale and boggy. My main differential is Moderate-Severe Persistent Allergic Rhinitis. I have counseled him on dust mite avoidance and would like to start him on a Mometasone nasal spray and daily Loratadine. I will plan to review him in one month."
XI. Summary & Further Reading
Top 3 Takeaways:
AR is a clinical diagnosis. Classify it using the ARIA guidelines (Duration + Severity) to guide your treatment.
Intranasal corticosteroids are the most effective first-line therapy for anyone with persistent or moderate-severe symptoms. Patient education on the technique is key.
Always check for and manage comorbidities, especially asthma and conjunctivitis. Treat the "one airway".
Key Resources:
International Guideline: Allergic Rhinitis and its Impact on Asthma (ARIA) Guidelines. The latest revision should be your primary guide. (https://www.aria-guidelines.org/)
Clinical Reference: UpToDate - "Allergic rhinitis: Clinical presentation, epidemiology, and diagnosis".
