About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Usually viral post-URTI — resolves in 2–3 weeks without antibiotics
- Facial pain/pressure, congestion, purulent discharge, hyposmia
- NICE NG79: no antibiotic if ≤10 days. High-dose nasal steroid (mometasone) if >10 days
- Back-up Rx: phenoxymethylpenicillin 5 days. Immediate: co-amoxiclav if systemically unwell
- Red flags: periorbital swelling (orbital cellulitis), severe headache, visual changes → urgent hospital
Overview
Acute rhinosinusitis is mucosal inflammation of the paranasal sinuses lasting <12 weeks. The vast majority are viral. Bacterial superinfection (S. pneumoniae, H. influenzae, M. catarrhalis) occurs in a minority — suggested by symptoms >10 days, biphasic illness, or severe unilateral pain. Maxillary sinuses most commonly affected.
Epidemiology
Affects 6–10% annually. Risk factors: viral URTI, allergic rhinitis, nasal polyps, deviated septum, dental infection, smoking.
Clinical Features
Symptoms
Facial pain/pressure worse bending forward
Nasal congestion and purulent discharge
Hyposmia/anosmia
Cough from postnasal drip
Periorbital swelling/redness — orbital complication
Severe frontal headache, meningism — intracranial complication
Persistent unilateral bloody discharge — exclude malignancy
Signs
Sinus tenderness on palpation
Purulent discharge on rhinoscopy
Periorbital oedema, proptosis, ophthalmoplegia — orbital abscess
Investigations
First-line
Clinical diagnosisNo imaging needed for uncomplicated acute sinusitis
Second-line
Nasal endoscopyIf recurrent/chronic — identify polyps, anatomical abnormalities
Specialist
CT sinusesNOT for uncomplicated cases — before FESS or if complications suspected
CT/MRI with contrastUrgently for orbital or intracranial complications
Management
NICE NG79 (Sinusitis — acute), 20171
Self-care
- Analgesia, saline irrigation
- Symptoms resolve in 2–3 weeks
2
Symptoms >10 days
- Nasal steroid: mometasone 200 mcg each nostril BD for 14 days
- Back-up Rx: phenoxymethylpenicillin 500 mg QDS 5 days if not improving in 7 more days
3
Immediate antibiotics
- If systemically very unwell: co-amoxiclav 500/125 mg TDS 5 days
4
Emergency referral
- Periorbital oedema/visual changes → orbital cellulitis → admit
- Severe headache/meningism → CT/MRI + IV antibiotics
Complications
- Orbital cellulitis/abscess: From ethmoid sinusitis through lamina papyracea — Chandler classification
- Intracranial: Frontal lobe abscess (Pott's puffy tumour), meningitis, cavernous sinus thrombosis
- Chronic sinusitis
UKMLA Exam Tips
- 1Clinical diagnosis — NO sinus X-rays or CT for uncomplicated cases
- 2≤10 days: self-care only. >10 days: nasal steroid ± back-up antibiotic
- 3First-line antibiotic: phenoxymethylpenicillin. Co-amoxiclav if immediate needed
- 4Swollen red eye + sinusitis = orbital cellulitis → emergency CT + IV antibiotics
- 5Pott's puffy tumour: frontal bone osteomyelitis + subperiosteal abscess
- 6Cavernous sinus thrombosis: bilateral eye signs, CN III/IV/V1/V2/VI palsies
practicetest your knowledge on acute sinusitisApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — ent and beyond.
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Acute Sinusitis: guidance by region
Recommendations, thresholds and pathways can differ. Open the page written for the jurisdiction you need.