Acute sinusitis
Under 10 days is almost always a cold. Antibiotics help little. Check the eyes every time.
A 30-year-old woman has had a blocked nose, pain over her cheeks and forehead, and green discharge for 6 days after a cold. Temperature 37.8 °C. She asks for antibiotics.
A 12-year-old boy has had sinusitis for a week and now has a swollen, red left eyelid. Moving his eye hurts, and he sees double looking to the side.
Who needs antibiotics, and who needs admission today?
- Eye or brain signsSwollen eyelid with painful or limited eye movements, double vision, reduced vision, severe headache, forehead swelling, confusion: admit.
- Under 10 daysUsually viral: no antibiotic.
- Over 10 days, or worsening after improvingNasal steroid spray, consider an antibiotic.
- Symptom reliefParacetamol or ibuprofen, saline rinses, steam.
- Antibiotic choiceAmoxicillin first, doxycycline or clarithromycin if allergic.
- Over 12 weeksChronic sinusitis: nasal steroid, saline rinses, ENT.
- Eyelid swelling with painful or reduced eye movement
- Double or reduced vision
- Severe frontal headache or forehead swelling (Pott's puffy tumour)
- Confusion, neck stiffness or fits
- Immunosuppressed or diabetic with black nasal crusts (fungal)
- Orbital cellulitis
- Intracranial abscess or meningitis
- Cavernous sinus thrombosis
- Dental source of maxillary sinusitis
- Invasive fungal sinusitis (diabetics, immunosuppressed)
- Sinonasal tumour (one-sided, bloody)
| Viral sinusitis | Most improve within 2–3 weeks |
| Nasal steroid (mometasone) | 2 sprays each nostril once daily for 14 days |
| Saline rinses | Several times a day |
| Amoxicillin | 500 mg 3 times daily for 5 days (when indicated) |
| Doxycycline | 200 mg on day 1, then 100 mg daily, 5 days total |
| Orbital cellulitis | IV antibiotics, CT, ENT and eye team |
Check every dose against a current drug reference and your hospital protocol.
On this page
Viral, bacterial or complicated?
- Viral
- symptom relief
- Nasal steroid
- consider amoxicillin
- Admit
- IV antibiotics
- CT
- ENT and eye team
Symptoms
- Blocked nose, discoloured discharge (front or down the throat), facial pain or pressure, reduced smell, fever.
- Discoloured discharge alone doesn't mean bacteria.
- Pain in several upper teeth, worse bending forward: maxillary sinusitis (or a dental cause).
Preseptal or orbital cellulitis?
| Feature | Preseptal (periorbital) | Orbital |
|---|---|---|
| Eyelid swelling | Yes | Yes |
| Pain on eye movement | No | Yes |
| Eye movements | Normal | Reduced |
| Proptosis | No | Often |
| Vision | Normal | May be reduced |
| Management | Oral antibiotics, close review (IV in young children) | Admit, IV antibiotics, CT, ENT and eye team |
Differential diagnosis
| Condition | Clues |
|---|---|
| Viral cold | Under 10 days, improving |
| Allergic rhinitis | Itch, sneezing, clear discharge, seasonal |
| Dental infection | Pain in one tooth, maxillary sinus on one side |
| Migraine | Headache with nausea and light sensitivity, no nasal symptoms |
| Sinonasal tumour | One-sided blockage, bloody discharge, facial numbness, older |
| Invasive fungal sinusitis | Diabetic or immunosuppressed, black crusts, facial numbness |
Treatment
- Saline rinses and steam help clear secretions.
- Avoid decongestant sprays for more than 5–7 days (rebound congestion).
Common mistakes
- Antibiotics for 5-day sinus symptoms.
- Missing orbital cellulitis because the child "just has a swollen eye".
- Long-term decongestant sprays.
- Missing a dental cause of one-sided maxillary sinusitis.
- Missing invasive fungal sinusitis in a diabetic.
Frequently asked questions
Does sinusitis need antibiotics?
Not usually. Most acute sinusitis is viral and improves within 2–3 weeks. Antibiotics are considered if symptoms last over 10 days or get worse after improving.
What are the danger signs in sinusitis?
Eyelid swelling with painful or reduced eye movements, double or reduced vision, severe headache, forehead swelling, confusion or neck stiffness.
Does green mucus mean a bacterial infection?
No. Discoloured discharge is common in viral infections too.
How long does sinusitis last?
Acute viral sinusitis usually improves within 2–3 weeks. Symptoms over 12 weeks are chronic sinusitis.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A woman has sinus symptoms for 6 days after a cold. What is the best management?
Answer: Symptom relief only. Most acute sinusitis is viral and improves within 2–3 weeks.
- Amoxicillin for 10 days: Not needed under 10 days.
- ENT referral: Not needed.
- CT sinuses: Not needed.
- Ciprofloxacin: No.
2. A child with sinusitis has a swollen red eyelid and pain on eye movement. What is the diagnosis?
Answer: Orbital cellulitis. Orbital cellulitis: admit, IV antibiotics, CT, ENT and eye team.
- Preseptal cellulitis: Eye movements are painless in preseptal.
- Allergy: No.
- Conjunctivitis: No.
- Stye: No.
3. When should an antibiotic be considered in acute sinusitis?
Answer: Over 10 days of symptoms. Prolonged or "double worsening" symptoms suggest bacterial infection.
- Facial pain on day 3: Usually viral.
- Fever on day 2: Usually viral.
- Any green discharge: Colour doesn't mean bacteria.
- All patients: No.
4. A young atopic man in Karachi has long-standing nasal obstruction and asymmetric polyps. CT shows expanded opacified sinuses with heterogeneous hyperdense areas; surgery reveals thick "peanut-butter" eosinophilic mucin with non-invasive fungal hyphae. What is the diagnosis?
Answer: Allergic fungal sinusitis. Fungal rhinosinusitis types: non-invasive — fungal ball (mycetoma; usually single maxillary sinus, older women, removal), allergic fungal rhinosinusitis (AFRS — immunocompetent atopic young adults in hot humid climates, common in South Asia; IgE-mediated hypersensitivity to fungi (Aspergillus, dematiaceous fungi) → eosinophilic mucin with Charcot–Leyden crystals and hyphae, nasal polyps, sinus expansion and bone thinning, heterogeneous hyperdensity on CT ("double density"), can cause proptosis); invasive — acute fulminant (Mucor/Aspergillus in DKA, neutropenia — black necrotic turbinates, rapid orbital/intracranial spread — emergency debridement + amphotericin), chronic invasive and granulomatous (Aspergillus flavus — Sudan, India, Pakistan). AFRS treatment: complete endoscopic surgery, then intranasal/oral steroids, saline irrigation; immunotherapy/antifungals in selected cases.
- Invasive fungal sinusitis: Invasive disease occurs in the immunocompromised.
- Fungal ball: A fungal ball lacks eosinophilic mucin and allergy.
- Bacterial sinusitis: This has fungal and allergic components.
5. A healthy adult has had nasal congestion, purulent discharge and facial pressure for 5 days after a cold, with no fever. When should antibiotics be considered?
Answer: Not now — consider after 10 days. Acute rhinosinusitis: < 12 weeks of nasal blockage/discharge plus facial pain/pressure or reduced smell. Most are viral (common cold); bacterial infection (Strep pneumoniae, H. influenzae, Moraxella) is suggested by symptoms > 10 days, double sickening (worsening after initial improvement), severe local pain, fever > 38 °C, purulent discharge, raised CRP/ESR. Management: analgesia, saline irrigation, intranasal steroid (if > 10 days), decongestant short-term; antibiotics only for suspected bacterial cases or systemically unwell/high-risk. Red flags (urgent referral): periorbital oedema, displaced globe, diplopia, reduced vision, severe frontal headache, frontal swelling, meningism, neurological signs. Chronic rhinosinusitis: > 12 weeks.
- Immediately, because pus is present: Purulence alone does not mean bacterial infection.
- After 2 days: Two days is too early; most viral cases settle.
- Only if CT abnormal: Acute sinusitis is a clinical diagnosis.
6. Which structure passes through the inferior orbital fissure?
Answer: Infraorbital nerve and vessels. The inferior orbital fissure transmits the infraorbital nerve and vessels (from the maxillary nerve), the zygomatic nerve and connections of the inferior ophthalmic vein to the pterygoid plexus. The superior orbital fissure transmits III, IV, V1 branches and VI. The ophthalmic artery passes through the optic canal.
- Trochlear nerve to superior oblique: Superior orbital fissure; a common answer-key error.
- Oculomotor nerve: Superior orbital fissure.
- Abducens nerve: Superior orbital fissure.
- Ophthalmic artery: Optic canal.
7. In cavernous sinus thrombosis, which cranial nerve is usually affected first, causing inability to look laterally?
Answer: Abducens nerve (VI). The abducens nerve runs through the middle of the cavernous sinus next to the internal carotid artery, while III, IV, V1 and V2 run in the lateral wall. So VI is often affected first, causing lateral rectus palsy and diplopia on looking to the side.
- Oculomotor nerve (III): In the lateral wall; affected later.
- Trochlear nerve (IV): In the lateral wall.
- Ophthalmic nerve (V1): In the lateral wall.
- Optic nerve (II): Not in the cavernous sinus.
References and dose sources
- NICE NG79 — Sinusitis (acute): antimicrobial prescribing
- Mometasone nasal spray dosing: Drugs.com: Mometasone nasal dosage (see also our mometasone nasal spray dose page)
- Amoxicillin dosing: Drugs.com: Amoxicillin dosage (see also our amoxicillin dose page)
- Doxycycline dosing: Drugs.com: Doxycycline dosage (see also our doxycycline dose page)
- Paracetamol dosing: Drugs.com: Acetaminophen (paracetamol) dosage (see also our paracetamol dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.