Overview
Acute Sinusitis
1. Clinical Overview
Summary
Acute sinusitis (rhinosinusitis) is inflammation of the paranasal sinuses lasting <12 weeks, usually following a viral upper respiratory tract infection. Most cases are viral and self-limiting. Bacterial sinusitis should be considered if symptoms worsen after 5 days or persist beyond 10 days.
Key Facts
| Aspect | Detail |
|---|---|
| Aetiology | Viral (vast majority), bacterial (<2%) |
| Duration | <12 weeks (usually <2-3 weeks) |
| Common Bacteria | S. pneumoniae, H. influenzae, M. catarrhalis |
| Complications | Orbital cellulitis, intracranial spread (rare) |
Clinical Pearls
- Double-worsening: Symptoms improving then worsening suggests bacterial superinfection
- Most cases viral: Antibiotics rarely needed
- Periorbital swelling: Red flag for orbital complications - urgent referral
- Maxillary/ethmoid: Most commonly affected sinuses
2. Epidemiology
Prevalence
| Population | Notes |
|---|---|
| Very common | Often follows URTI |
| Peak seasons | Autumn/Winter |
| Recurrence | Common if allergic rhinitis |
Risk Factors
| Risk Factor | Association |
|---|---|
| Viral URTI | Preceding infection |
| Allergic rhinitis | Mucosal inflammation |
| Nasal polyps | Sinus obstruction |
| Dental infection | Maxillary spread |
| Smoking | Impaired mucociliary clearance |
| Immunocompromise | Fungal sinusitis risk |
3. Pathophysiology
Mechanism
Viral URTI
↓
Mucosal Oedema → Sinus Ostia Obstruction
↓
Impaired Ventilation + Mucus Retention
↓
Local Inflammation → ACUTE SINUSITIS
↓ (if prolonged/obstruction persists)
Bacterial Superinfection (minority)
Sinus Drainage
| Sinus | Drains to |
|---|---|
| Frontal | Middle meatus |
| Maxillary | Middle meatus |
| Anterior ethmoid | Middle meatus |
| Posterior ethmoid | Superior meatus |
| Sphenoid | Sphenoethmoidal recess |
4. Clinical Presentation
Symptoms
| Symptom | Description |
|---|---|
| Facial pain/pressure | Worse on bending forward |
| Nasal congestion | Bilateral usually |
| Purulent discharge | Anterior or post-nasal drip |
| Reduced smell | Hyposmia |
| Headache | Frontal, maxillary |
| Fever | May be present in bacterial |
| Toothache | Upper teeth (maxillary sinus) |
Suggesting Bacterial Sinusitis
| Feature | Notes |
|---|---|
| Duration >10 days | Without improvement |
| Double-worsening | Improve then worsen |
| High fever (>39°C) | Purulent discharge |
| Severe symptoms | Facial pain, headache |
5. Clinical Examination
Findings
| Finding | Location |
|---|---|
| Tenderness | Over maxillary, frontal sinuses |
| Purulent discharge | Anterior nares, posterior pharynx |
| Mucosal oedema | Inferior turbinates, middle meatus |
| Transillumination | Reduced (not reliable) |
Red Flag Signs
| Finding | Concern |
|---|---|
| Periorbital oedema/erythema | Orbital cellulitis |
| Proptosis | Orbital abscess |
| Restricted eye movements | Orbital involvement |
| Reduced visual acuity | Orbital complication |
| Meningeal signs | Intracranial spread |
| Altered consciousness | Intracranial spread |
6. Investigations
Usually Not Required
- Diagnosis is clinical
When to Investigate
| Indication | Test |
|---|---|
| Suspected complications | CT sinuses/orbits |
| Recurrent/chronic | CT, nasal endoscopy |
| Suspected malignancy | CT, MRI, biopsy |
7. Management
Self-Care (Viral - Most Cases)
| Measure | Details |
|---|---|
| Analgesia | Paracetamol/ibuprofen |
| Saline irrigation | May help symptoms |
| Hydration | Fluids |
| Duration | Resolves in 2-3 weeks |
Pharmacological
| Treatment | Indication |
|---|---|
| Nasal decongestant (short-term) | Xylometazoline - max 7 days |
| Intranasal corticosteroid | Mometasone - if symptoms >10 days |
| Antibiotic | Only if severe/worsening after 10 days |
Antibiotics (when indicated)
| Drug | Choice |
|---|---|
| Phenoxymethylpenicillin | First-line (500mg QDS x 5 days) |
| Co-amoxiclav | If severe or penicillin-failure |
| Doxycycline | Penicillin allergy |
Indications for Antibiotic
- Symptoms >10 days without improvement
- Severe symptoms at presentation
- High fever with purulent discharge
- Immunocompromised patients
Referral Indications
| Indication | Urgency |
|---|---|
| Orbital complications | Urgent/same-day |
| Recurrent (≥3/year) | ENT |
| Chronic (>12 weeks) | ENT |
| Nasal polyps | ENT |
8. Complications
| Complication | Notes |
|---|---|
| Orbital cellulitis | From ethmoid sinusitis |
| Subperiosteal/orbital abscess | Requires surgery |
| Cavernous sinus thrombosis | Life-threatening |
| Meningitis | Intracranial spread |
| Frontal bone osteomyelitis | "Pott's puffy tumour" |
9. Prognosis & Outcomes
| Factor | Outcome |
|---|---|
| Viral sinusitis | Self-limiting, 2-3 weeks |
| Bacterial (treated) | Resolves with antibiotics |
| Complications | Rare but serious |
10. Evidence & Guidelines
| Organisation | Key Points |
|---|---|
| NICE NG79 | Delayed antibiotic strategy, steroids if >10 days |
| EPOS | European guidelines on rhinosinusitis |
11. Patient / Layperson Explanation
What is sinusitis? It's inflammation of the air spaces (sinuses) behind your cheeks, forehead, and nose. It usually happens after a cold.
Is it bacterial? Usually not - most sinusitis is caused by viruses. Antibiotics won't help unless it's bacterial.
How do I know if I need antibiotics? You probably don't. See your doctor if:
- Symptoms last more than 10 days without getting better
- You're getting worse after initially improving
- You have severe pain or high fever
What can I do?
- Take painkillers (paracetamol or ibuprofen)
- Rinse your nose with salt water spray
- Use a decongestant spray for a few days (no more than 7)
- Stay hydrated
When should I seek urgent help?
- Swelling or redness around your eyes
- Double vision or vision problems
- Severe headache with neck stiffness
- Confusion
12. References
- NICE NG79. Sinusitis (acute): antimicrobial prescribing. 2017.
- Fokkens WJ, et al. EPOS 2020 Guidelines. Rhinology. 2020.
- Rosenfeld RM, et al. AAO-HNS Sinusitis Guidelines. 2015.