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Acute rhinosinusitis
Most acute rhinosinusitis is viral and settles on its own; suspect bacterial infection only when symptoms last 10 days or more without improvement, when a second worsening follows initial improvement, or when the onset is severe with high fever and purulent discharge — and only then consider antibiotics.
Why it matters in the exam
In the exam the question almost always turns on one decision: viral or bacterial, and are antibiotics needed. The time definitions matter: acute rhinosinusitis lasts less than 12 weeks, chronic 12 weeks or more, and recurrent acute rhinosinusitis is 4 or more episodes per year with full recovery in between. The bacterial presentation is defined by one of three patterns: symptoms lasting 10 days or more without improvement, "double sickening" after initial improvement, or a severe onset with fever of 39 degrees or more and purulent discharge or facial pain for 3 to 4 consecutive days.
The usual bacteria are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. The preferred treatment is amoxicillin, with or without clavulanic acid, for 5 to 10 days in adults; in an adult with non-severe illness and assured follow-up, watchful waiting is also acceptable. With penicillin allergy choose doxycycline or a respiratory fluoroquinolone (levofloxacin or moxifloxacin). Macrolides and trimethoprim-sulfamethoxazole are not advised, since pneumococcal resistance to them is high.
Imaging is not needed in uncomplicated acute rhinosinusitis, and plain sinus films add nothing. Contrast CT is needed only when a complication is suspected — periorbital swelling, visual change, severe headache, neurological signs or meningism. Helpful adjuncts are saline irrigation and an intranasal steroid; antihistamines and prolonged decongestants are not recommended.
Key points
- Most acute rhinosinusitis is viral.
- Bacterial: 10 days without improvement, double sickening, or severe onset.
- First line: amoxicillin with or without clavulanate.
- Penicillin allergy: doxycycline or a respiratory fluoroquinolone.
- Imaging only when a complication is suspected.
Summary table
| Situation | Definition or clue | Approach |
|---|---|---|
| Viral rhinosinusitis | Less than 10 days, improving | Symptomatic care: saline irrigation, analgesia |
| Suspected bacterial — persistent | 10 days or more without improvement | Amoxicillin, or watchful waiting in an adult |
| Suspected bacterial — double sickening | New worsening after improvement | Amoxicillin-clavulanate |
| Suspected bacterial — severe onset | Fever 39 degrees or more and purulent discharge for 3 to 4 days | Antibiotics at once |
| Penicillin allergy | Rash or immediate reaction | Doxycycline or a respiratory fluoroquinolone |
| Suspected complication | Eyelid swelling, reduced vision, neurological signs | Contrast CT and admission |
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Sources
- EPOS 2020: European Position Paper on Rhinosinusitis and Nasal Polyps, 2020 — Acute rhinosinusitis in adults and children
- AAO-HNS Clinical Practice Guideline: Adult Sinusitis (Update), 2015 — Acute bacterial rhinosinusitis
- IDSA Clinical Practice Guideline for Acute Bacterial Rhinosinusitis in Children and Adults, 2012 — Antimicrobial choice
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.