Acute and chronic rhinosinusitis

At a glance

• Acute rhinosinusitis (under 12 weeks) is almost always viral and resolves without antibiotics. Its infective side is covered in the URTI note.
• Chronic rhinosinusitis (CRS) is an inflammatory disease, not a chronic infection. It affects about 5 to 10% of adults and is split by endotype into type 2 (eosinophilic, usually with polyps) and non-type 2.
• Medical treatment is saline irrigation plus intranasal corticosteroid, then surgery or a biologic for refractory polyps.
• Always look for a secondary cause when it is unilateral, starts in childhood or comes with systemic illness.
• EPOS 2020 is still the current European position paper; the 2024 EPOS/EUFOREA paper defines control and treatment response for CRSwNP.

Definitions

Term	EPOS 2020 diagnostic definition
Acute rhinosinusitis	Sudden onset of 2 or more symptoms (blockage or discharge, plus facial pain or reduced smell) for under 12 weeks
Acute post-viral	Worsening after 5 days or persisting beyond 10 days
Acute bacterial	At least 3 of: discoloured discharge, severe local pain, fever over 38°C, raised CRP or ESR, double sickening (a diagnostic definition; the IDSA antibiotic indications use fever over 39°C)
Recurrent acute	4 or more episodes a year with symptom-free intervals
Chronic (CRS)	12 weeks or more of the same symptoms, confirmed on nasendoscopy (polyps, mucopurulent discharge, oedema at the middle meatus) or CT

• Pitfall: facial pain or headache without nasal blockage or discharge is rarely sinus disease. Think migraine or midfacial segmental pain (see headache).

Acute rhinosinusitis in brief

• Symptomatic care: saline, analgesia, intranasal corticosteroid.
• Antibiotics only for the bacterial features in the card (Therapeutic Guidelines: amoxicillin for 5 days).
• Red flags needing same-day CT and specialist review: periorbital oedema or erythema, displaced globe, diplopia, ophthalmoplegia, reduced acuity, severe unilateral or frontal headache, frontal swelling (Pott puffy tumour), meningism or focal neurology.
• Neutropenia or uncontrolled diabetes with facial pain, black eschar or cranial nerve palsy: invasive fungal sinusitis (mucormycosis) is a surgical emergency.

Classification of chronic rhinosinusitis

	Type 2	Non-type 2
Typical phenotype	CRS with nasal polyps (CRSwNP), eosinophilic CRS, allergic fungal rhinosinusitis, N-ERD	CRS without polyps (CRSsNP)
Markers	Tissue eosinophils at least 10/hpf, blood eosinophils at least 150/µL, total IgE at least 100 kU/L	Neutrophilic, normal IgE
Associations	Late-onset asthma, smell loss, NSAID sensitivity	Smoking, reflux, recurrent infection
Responds to	Corticosteroids, biologics	Macrolides, surgery

Secondary CRS

• Localised (usually unilateral): odontogenic sinusitis, fungal ball (maxillary, in immunocompetent people), tumour (inverted papilloma, carcinoma).
• Diffuse: cystic fibrosis (polyps in a child are CF until proven otherwise), primary ciliary dyskinesia, immunodeficiency (CVID, specific antibody deficiency, HIV), granulomatosis with polyangiitis (crusting, epistaxis, saddle nose, ANCA), EGPA (polyps, late asthma, eosinophilia), sarcoidosis.

Recognition

• Nasal blockage, discharge or postnasal drip, facial pressure, and reduced or lost smell (the most specific symptom for polyps).
• Anterior rhinoscopy may show polyps; nasendoscopy is the standard.
• SNOT-22 (0 to 110) tracks symptom burden. A score of 40 or more indicates significant impairment.
• Ask about asthma, aspirin or NSAID reactions, dental problems and recurrent chest infections.

Investigations

• Nasendoscopy by ENT.
• CT sinuses after a trial of medical therapy or when planning surgery, not for uncomplicated acute disease. The Lund-Mackay score grades opacification (0 to 24).
• Bloods to define endotype and secondary causes: FBC with eosinophils, total IgE, immunoglobulins and vaccine responses (recurrent infections), ANCA if crusting or bleeding.
• Skin prick tests or specific IgE if allergic rhinitis coexists.
• Sweat test or CF genetics for polyps in a child or young adult.

Management

Medical

• High-volume saline irrigation daily.
• Intranasal corticosteroid, as a spray or as budesonide added to saline rinses for better sinus delivery after surgery.
• Short oral corticosteroid courses for CRSwNP shrink polyps and restore smell for weeks. Limit to 1 to 2 courses a year: cumulative doses of a few grams raise the risk of osteoporosis, diabetes and cataract (see glucocorticoid complications).
• Long-term low-dose macrolide (at least 3 months) for CRSsNP with normal IgE. Check the QT interval and interactions; stop if no benefit at 3 months.
• Antibiotics only for acute bacterial exacerbations.
• Treat coexisting allergic rhinitis and asthma; see allergic rhinitis.

Surgery

• Endoscopic sinus surgery (ESS) when appropriate medical therapy has failed. Polyps recur in many patients within 5 to 10 years, particularly with N-ERD and asthma.
• Fungal balls and odontogenic disease need surgical or dental source control.

Biologics for CRSwNP

• EPOS 2020 criteria, as updated by EPOS/EUFOREA 2023: bilateral polyps plus 3 of the 5 below after previous ESS, or (EPOS 2020) 4 of 5 in patients who haven't had surgery or can't have it:
  • type 2 evidence (tissue eosinophils at least 10/hpf, blood eosinophils at least 150/µL or total IgE at least 100 kU/L). The 2023 update lowered the blood eosinophil cut-off from 250 to match GINA
  • systemic corticosteroids at least twice in a year, or long term (over 3 months)
  • SNOT-22 of 40 or more
  • anosmia
  • comorbid asthma needing regular inhaled corticosteroid
• Dupilumab (anti-IL-4Rα; SINUS-24 and SINUS-52), omalizumab (POLYP 1 and 2) and mepolizumab (anti-IL-5; SYNAPSE) all reduce polyp size, steroid use and need for surgery.
• Australia: mepolizumab has been PBS-listed for severe CRSwNP since 1 April 2023. Dupilumab's PBS listings cover atopic dermatitis and asthma, not polyps. PBS rules prevent two biologics being used together for polyps and asthma. In the pipeline: omalizumab for CRSwNP was PBAC-recommended in May 2025 but still not listed for polyps in March 2026, and tezepelumab (WAYPOINT) was on the November 2026 PBAC agenda. Check the current Schedule.
• Response is reassessed at 6 months and then yearly using polyp size, smell, SNOT-22, steroid need and impact of asthma.

N-ERD (aspirin-exacerbated respiratory disease)

• CRSwNP, asthma and respiratory reactions (congestion, wheeze) to aspirin and COX-1 inhibitors. Onset usually in the third or fourth decade.
• Avoid COX-1 NSAIDs. Paracetamol at standard doses and COX-2 inhibitors are usually tolerated.
• Aspirin desensitisation followed by daily aspirin, usually after ESS, reduces polyp regrowth. Dupilumab is particularly effective. See the asthma note.

Pitfalls

• Repeated antibiotic courses for CRS, which is inflammatory.
• Diagnosing "sinus headache" without nasal symptoms or endoscopic findings.
• Missing unilateral disease: tumour, fungal ball or dental source.
• Polyps in a child without a sweat test.
• Crusting and epistaxis without ANCA.
• Repeated oral steroid courses without counting the cumulative dose.