ENT & Family Medicine & Infectious Diseases
Sinusitis (rhinosinusitis)
Sinusitis—now referred to as rhinosinusitis in international medical terminology to reflect the nearly constant and simultaneous involvement of the nasal mucosa and paranasal sinuses (since the nasal and sinus mucosa are anatomically and inflammatorily continuous)—is the inflammation of the mucous membrane lining the sinus cavities (maxillary, ethmoid, frontal, and sphenoid), most often triggered by a viral infection of the upper respiratory tract (rhinovirus, seasonal coronaviruses, influenza, RSV) in the context of the common cold, with obstruction of the sinus ostium, accumulation of secretions, and a predisposition to secondary bacterial superinfection in a minority of cases. Acute rhinosinusitis is one of the most common conditions in primary care—accounting for nearly 20 million annual medical visits in the United States—and one of the leading causes of antibiotic prescriptions in Western countries, despite the fact that 90 to 98% of acute rhinosinusitis cases are viral in origin and do not require antibiotics. Canadian clinical guidelines (CMAJ + IDSA) emphasize the distinction between viral rhinosinusitis (symptomatic treatment only—duration 7–10 days) and acute bacterial rhinosinusitis (antibiotics only if 3 specific criteria are met: see below) to reduce inappropriate antibiotic prescribing and preserve their effectiveness. Chronic rhinosinusitis (CRS—duration > 12 weeks) is a distinct condition, often associated with allergic rhinitis + nasal polyposis + mucociliary dysfunction + or a deviated septum, requiring a different therapeutic approach focused on intranasal corticosteroids + nasal irrigation + and sometimes endoscopic sinus surgery.
Diagnostic Criteria and Viral vs. Bacterial Distinction
- Acute viral rhinosinusitis (common cold) Symptoms < 10 days + ongoing improvement + 4 cardinal symptoms: nasal congestion + rhinorrhea (clear or colored) + facial (sinus) pressure or pain + reduced sense of smell + color of secretions (yellow + green) is NOT a criterion for bacteremia → treatment: symptomatic only
- Acute bacterial rhinosinusitis — IDSA criteria (3 scenarios):
- Scenario 1 — Persistent symptoms ≥ 10 days with no improvement: Rhinorrhea + congestion + facial pressure lasting > 10 days without improvement → viral sinusitis does not last > 10 days
- Scenario 2 — Worsening following initial improvement (double worsening): Symptoms improving after D5–D7 then worsening with fever + increased nasal discharge + facial pain → bacterial superinfection on initial viral rhinosinusitis
- Scenario 3 — Sudden severe symptoms: Fever ≥ 39°C + intense unilateral facial pain + unilateral dental pain → probable bacterial rhinosinusitis from onset
Bacteria responsible for acute bacterial rhinosinusitis
- Streptococcus pneumoniae Pneumococcus 30–40 % → primary cause + increasing penicillin resistance (PSPN + PSPI) → standard-dose amoxicillin remains effective if MIC ≤ 2 µg/mL
- Haemophilus influenzae non-typable 20–30% of % strains → beta-lactamase production in 30–40% of % strains → amoxicillin-clavulanate if beta-lactamase is suspected
- Moraxella catarrhalis : 10–20 % → nearly constant beta-lactamase production (90 %) → amoxicillin-clavulanate
- Anaerobes (odontogenic dental sinusitis): Bacteroides + Fusobacterium + Prevotella → maxillary sinusitis associated with recent tooth extraction + or apical abscess + treatment: amoxicillin-clavulanate + or metronidazole
Acute rhinosinusitis treatment
| Situation | Recommended treatment | Duration and remarks |
|---|---|---|
| Viral rhinosinusitis (< 10 days + no worsening) | Symptomatic treatment only: nasal irrigation with NaCl (normal saline or hypertonic saline) + topical nasal decongestants (oxymetazoline 0.1% 1–3 times daily for up to 3–5 days) + acetaminophen or NSAIDs for pain + intranasal corticosteroids (fluticasone + mometasone) if underlying allergic rhinitis + NO antibiotics | Spontaneous resolution within 7–10 days for the vast majority; 2–3% progress to bacterial sinusitis; antibiotics do not shorten the duration of symptoms in viral sinusitis |
| Mild to moderate bacterial rhinosinusitis (1 of 3 IDSA criteria) | Amoxicillin 500–875 mg x 2–3/day x 5–7 days (adult) or amoxicillin 40–45 mg/kg/day x 5–7 days (child) or armed waiting 2–3 days with symptomatic treatment if symptoms are mild (Canadian guidelines «wait-and-see» option) | Spontaneous recovery rate of 60–70% for % even without antibiotics → the decision must weigh the benefits against the risk of resistance + prefer narrow-spectrum amoxicillin as first-line treatment |
| Severe bacterial rhinosinusitis (fever ≥ 39°C + intense pain) or amoxicillin failure at 72 hours | Amoxicillin-clavulanate 875/125 mg × 2/day × 7–10 days (adult) OR levofloxacin 500 mg × 1/day × 5 days (non-anaphylactic penicillin allergy) OR ceftriaxone 1 g IM/IV for very severe forms | Covers H. influenzae + M. catarrhalis beta-lactamases + true penicillin allergy: aztreonam (parenteral) + or respiratory quinolone |
| Acute Rhinosinusitis in Children (Bacteriological Criteria Met) | Amoxicillin 45-90 mg/kg/day × 10 days (high dose if resistant pneumococcus or daycare + or recent antibiotic therapy < 3 months) | Duration 10 days in children (vs 5–7 days in adults) + amoxicillin-clavulanate if beta-lactamase suspected |
Chronic rhinosinusitis (CRS)
- Definition: Symptoms of rhinosinusitis ≥ 12 weeks despite adequate medical treatment + confirmed by nasal endoscopy + or sinus CT scan (mucosal thickening + opacification)
- Shapes CRS with nasal polyps (CRSwNP) - bilateral nasal polyps + often associated with the Yenner triad (asthma + aspirin sensitivity + polyps) + type 2 (eosinophilic) + or CRS without nasal polyps (CRSsNP) - neutrophilic + often linked to septal deviation + recurrent infections
- Medical treatment: Daily intranasal corticosteroid spray (fluticasone + mometasone + budesonide) for at least 3–6 months → reduction in polyp size + improved sinus drainage + hypertonic nasal rinses (2% NaCl — squeeze bottle) × 2/day → clearance of secretions + improvement in mucus + oral corticosteroids (prednisone 0.5 mg/kg/day × 2 weeks) during acute polyposis flare-ups
- Biotherapies (Severe refractory RSCaPN type 2): dupilumab (Dupixent® — anti-IL-4/IL-13) 300 mg SC every 2 weeks → Health Canada approved for severe type 2 eosinophilic chronic rhinosinusitis refractory to corticosteroid therapy + significant reduction in polyp volume + improved sense of smell + mepolizumab (anti-IL-5) + omalizumab (anti-IgE if associated allergic asthma)
- Functional Endoscopic Sinus Surgery (FESS): if medical treatment has failed for ≥ 3 months + or complications are present + or there is extensive polyposis + under general anesthesia + results: 75–85% improvement in long-term symptoms + surgery does not cure chronic sinusitis but significantly improves quality of life + sinus patency + and response to postoperative medical treatments
ℙ️
The green or yellow color of nasal discharge does NOT indicate bacterial sinusitis requiring antibiotics. This coloration simply reflects the presence of neutrophils mobilized against the virus—it's part of the normal progression of viral rhinosinusitis between days 3 and 7. The true criteria for a bacterial superinfection are duration (> 10 days with no improvement) OR biphasic worsening after initial improvement OR severe symptoms from the outset (fever ≥ 39°C + intense unilateral pain).
Complications — urgencies to recognize
- Orbital cellulitis (preseptal or postseptal): Ethmoidal sinusitis extension → periorbital edema + erythema + pain → if postseptal: proptosis + limited eye movements + diplopia + vision loss → ophthalmological and ENT emergency + CT scan of orbits + sinuses + IV antibiotics + surgical drainage if abscess
- Intracranial abscess (subdural empyema + epidural abscess + brain abscess): severe headaches + fever + focal neurological signs + nuchal rigidity → urgent brain MRI + neurosurgery + intensive care
- Secondary bacterial meningitis: extension of sphenoidal or ethmoidal sinusitis + stiff neck + severe headaches → lumbar puncture + urgent ceftriaxone
- Frontal osteomyelitis (Pott's tumor) Frontal sinus extension → painful + fluctuant frontal swelling + frontal CT scan + prolonged antibiotics + surgery
- Isolated sphenoid sinusitis often unknown → very intense retro-orbital and occipital headaches + without obvious rhinorrhea + risk of intracranial extension + urgent CT or MRI
Urgent medical consultation
Consult a doctor for sinusitis accompanied by swelling or redness around the eyes, difficulty opening the eye, blurred vision, severe headaches, neck stiffness, confusion, or a very high fever (≥ 39.5°C) unresponsive to antipyretics—these signs suggest an orbital or intracranial complication of sinusitis, a medical and surgical emergency. For sinusitis evaluation, antibiotic prescription if bacterial criteria are met, nasal washes, and intranasal corticosteroids, Clinique Omicron offers medical consultations at its service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's doctors and nurse practitioners (NPs) diagnose and differentiate viral rhinosinusitis (symptomatic treatment) from bacterial rhinosinusitis (IDSA criteria — antibiotics if indicated), prescribe amoxicillin or amoxicillin-clavulanate based on severity and risk factors, recommend nasal rinses and intranasal corticosteroids, recognize orbital and intracranial complications requiring urgent referral, and manage chronic rhinosinusitis with referral to an ENT for FESS if necessary. Consultations are available at several service locations in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and is not a substitute for medical advice from a doctor or an ENT. The vast majority of acute sinusitis cases are viral and resolve spontaneously without antibiotics in 7 to 10 days — antibiotics are only indicated if the criteria for bacterial sinusitis are met according to Canadian guidelines. The color of nasal discharge is not a criterion for prescribing antibiotics.
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