Sinusitis

Definition

Sinusitis is inflammation of the lining of the paranasal sinuses. Because that lining is continuous with the lining of the nose and the two are almost never inflamed separately, the accurate term is rhinosinusitis, and the European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS) defines it as nasal blockage or discharge, with facial pain or pressure or a reduced sense of smell, supported by examination or imaging.¹ It is classified by duration:

• Acute rhinosinusitis — up to 4 weeks. Overwhelmingly viral; a small minority becomes bacterial.
• Recurrent acute rhinosinusitis — four or more discrete episodes a year, with full recovery in between.
• Chronic rhinosinusitis — 12 weeks or longer of continuous symptoms, subdivided into chronic rhinosinusitis without nasal polyps and chronic rhinosinusitis with nasal polyps, which behave differently and are treated differently.¹

The distinction is the whole basis of correct treatment: acute disease is usually self-limiting and needs symptom relief, while chronic disease is an inflammatory condition needing sustained topical anti-inflammatory treatment — not repeated antibiotics.

Pathophysiology

Each sinus drains through a narrow opening into the nose, most of them converging on a small area beneath the middle turbinate called the ostiomeatal complex. Normal function depends on three conditions: a patent opening, working mucociliary clearance, and normal mucus. Sinusitis follows when any of the three fails.²

In acute viral rhinosinusitis, viral infection causes mucosal oedema that obstructs the ostia; secretions are retained, ciliary function is impaired and pressure builds — producing facial pain and congestion without bacterial infection. In most people the mucosa recovers within seven to ten days. Where obstruction persists, retained secretions may become secondarily infected with Streptococcus pneumoniae, Haemophilus influenzae or Moraxella catarrhalis, producing acute bacterial rhinosinusitis.³

In chronic rhinosinusitis, the process is inflammatory rather than infective, with epithelial barrier dysfunction, impaired clearance, biofilm formation and mucosal remodelling. Two broad patterns are recognised: type 2 inflammation, eosinophil-driven, associated with polyps, asthma and loss of smell; and non-type 2 inflammation, more neutrophilic, associated with facial pressure, thick discharge and infective exacerbations. The distinction matters because it predicts response to topical corticosteroid, to surgery and to biologic therapy.²

Co-morbidities

Commonly associated: allergic and non-allergic rhinitis, nasal polyps, asthma, bronchiectasis, dental disease affecting the upper molars, gastro-oesophageal reflux, obstructive sleep apnoea, immunodeficiency (particularly common variable immunodeficiency and specific antibody deficiency), cystic fibrosis and primary ciliary dyskinesia, smoking, and diabetes or immunosuppression — which change the risk profile of acute disease substantially.²

Prevalence

Acute rhinosinusitis is one of the most common reasons for a primary care visit and for an antibiotic prescription; most adults experience at least one episode of viral rhinosinusitis a year as part of an upper respiratory tract infection. Chronic rhinosinusitis affects an estimated 5–12% of adults in European and North American population surveys, with figures at the lower end when endoscopy or imaging is required rather than symptoms alone.¹ Around 1.5% of Australians report chronic sinusitis as a long-term condition, and it accounts for a large share of both antibiotic use and ear, nose and throat referrals — most of the antibiotic use being for the acute form, where it is largely unnecessary.⁴

Causes and risk factors

• Viral upper respiratory tract infection — the trigger for the great majority of acute episodes.
• Allergic and non-allergic rhinitis — persistent mucosal swelling obstructs sinus drainage.¹
• Anatomical factors — marked septal deviation, concha bullosa, narrow ostiomeatal complex; relevant mainly in recurrent or one-sided disease.
• Impaired mucociliary clearance — cystic fibrosis, primary ciliary dyskinesia, prior surgery or trauma, and smoking, which is directly ciliotoxic.
• Immunodeficiency — consider in recurrent, severe or treatment-resistant disease, particularly with recurrent chest or ear infection.
• Dental infection — the roots of the upper molars sit in the floor of the maxillary sinus; odontogenic disease is a recognised and frequently missed cause of one-sided maxillary sinusitis.²
• Environmental and occupational exposure — dust, smoke, fumes, chlorinated pools, and pressure change from diving and flying.
• Fungal disease — allergic fungal rhinosinusitis, and invasive fungal sinusitis in the immunocompromised, which is a medical emergency.¹

Symptoms

• Nasal blockage and thick nasal or post-nasal discharge, often discoloured.
• Facial pain, pressure or fullness — over the cheeks, between or above the eyes, sometimes felt in the upper teeth; typically worse leaning forward.
• Reduced sense of smell, partial in most chronic disease and often complete where polyps are present.
• Cough, often worse at night, and chronic throat clearing.
• Fever in acute disease; systemic upset and fatigue.
• Ear fullness, headache, halitosis and disturbed sleep.

Telling viral from bacterial in acute disease

The distinction is made on the pattern over time, not on the colour of the mucus — discoloured discharge reflects neutrophils and appears in ordinary viral infection. Bacterial infection is suggested by any of three patterns: symptoms persisting beyond ten days without improvement; severe symptoms from the outset with fever above 39 °C and purulent discharge for three or more consecutive days; or "double worsening" — a clear deterioration after an initial improvement.³ Fewer than one in twenty episodes of acute rhinosinusitis is bacterial.⁵

The pattern in chronic disease

Chronic rhinosinusitis is dominated by blockage, discharge, pressure and smell loss rather than by pain. Isolated facial pain without nasal symptoms is usually not sinusitis — it is far more often a primary headache disorder, most commonly migraine, and repeated antibiotics for "sinus headache" are one of the most common patterns of avoidable treatment.²

Warning signs

Diagnosis

Why diagnosis matters

Two very different errors are common. Acute rhinosinusitis is over-treated with antibiotics that make little difference to a self-limiting illness while contributing to resistance and adverse effects.⁵ Chronic rhinosinusitis is under-treated, because it is managed as a series of infections rather than as one persistent inflammatory disease — so patients receive repeated short antibiotic courses and never a sustained trial of topical corticosteroid and saline, which is what actually works.¹

How is it diagnosed?

Clinically, from symptom pattern and duration. Acute rhinosinusitis needs no imaging and no swabs: the diagnosis is the history. Chronic rhinosinusitis requires twelve weeks or more of the defining symptoms plus objective confirmation — mucosal disease, discharge or polyps on nasal endoscopy, or mucosal change on computed tomography (CT). Symptoms alone over-diagnose it substantially, which is why the objective step is part of the definition.¹

Imaging

Plain sinus X-rays are obsolete and should not be used. CT of the sinuses is the imaging test of choice, but it is for confirming chronic disease, assessing extent, planning surgery and investigating complications or one-sided disease — not for diagnosing an acute episode.² Incidental mucosal thickening is present in a large proportion of asymptomatic people, so a CT report must be interpreted against symptoms rather than treated on its own. Magnetic resonance imaging is added where tumour, fungal disease or intracranial extension is suspected.

Microbiology

Nasal swabs correlate poorly with the organisms actually in the sinus and rarely change management. Endoscopically guided culture from the middle meatus, or aspirate at surgery, is reserved for treatment failure, immunocompromise, suspected resistant organisms or complications.²

Investigations for related conditions

• Spirometry with reversibility testing where there is cough, wheeze or exercise limitation — asthma and chronic rhinosinusitis coexist frequently and each worsens the other.⁷
• Allergy testing — skin prick testing or allergen-specific immunoglobulin E where an allergic contribution is suspected.
• Immune workup — immunoglobulins with subclasses, and specific antibody responses — in recurrent, severe or refractory disease, especially with recurrent chest infection.
• Cystic fibrosis and ciliary investigations in children, young adults, or anyone with bronchiectasis and lifelong wet cough.
• Dental assessment and imaging for one-sided maxillary disease.
• Antineutrophil cytoplasmic antibody testing where crusting, bleeding or destructive change suggests vasculitis.
• Chest imaging where bronchiectasis is suspected — the upper and lower airway are commonly affected by the same underlying disorder.²

Management

Management and goals

For acute disease the goal is symptom relief and safe recovery, with antibiotics reserved for the minority who need them. For chronic disease the goal is control of persistent inflammation: a nose that can be breathed through, no more than occasional flares, recovery of as much sense of smell as the disease allows, stable asthma, and no reliance on repeated antibiotic or oral steroid courses. Chronic treatment is judged over weeks to months, and stopping as soon as symptoms improve is the usual reason control is lost.

Acute rhinosinusitis

Where antibiotics are indicated, first-line choice follows Australian therapeutic guidance rather than habit, and the course is short. "Delayed prescribing" — a script to be filled only if there is no improvement in a defined number of days — is a reasonable middle path in primary care.⁴

Chronic rhinosinusitis

Saline rinsing — how to do it properly

Recognising deterioration

In acute disease: no improvement by ten days, deterioration after initial improvement, high fever, or any of the warning signs above. In chronic disease: increasing blockage, returning smell loss, thicker or bloodstained discharge, new or one-sided facial pain, worsening asthma, or more frequent need for antibiotics or oral steroids — each of which is a reason for reassessment rather than another course of the same treatment.

Action plan

A written plan should state the daily saline and topical steroid routine, what to do in a flare and for how long, when antibiotics are and are not appropriate, the specific warning signs requiring urgent care, and the review interval. Where asthma coexists, the asthma action plan sits alongside it — sinus flares and asthma flares travel together.⁷

Medications

Medications for sinusitis

Correct use of medications

Intranasal corticosteroid is a preventer: daily use, correct technique, and weeks before full effect. Sprays cannot reach an obstructed sinus, which is why rinsing first matters and why a corticosteroid rinse is often used after surgery. Topical decongestants must be limited to a few days. And an antibiotic is a treatment for a specific bacterial episode — a chronic condition treated with recurrent short courses stays chronic.⁹

Order of medications

Analgesia as needed; saline rinse first; medicated spray a few minutes later onto a cleared nose; decongestant only for the first few days of a severe acute episode. In chronic disease, saline plus topical corticosteroid should be given a properly supervised trial of at least eight to twelve weeks before anything is declared to have failed.¹

Multi-system manifestations

Orbital and intracranial complications

The sinuses are separated from the orbit by a paper-thin plate of bone and from the brain by the roof of the ethmoid and frontal sinuses, so untreated acute infection can spread directly. Orbital cellulitis and abscess — swelling, pain, restricted or double vision, reduced acuity — threaten sight. Intracranial spread produces meningitis, subdural empyema, brain abscess or cavernous sinus thrombosis, with headache, confusion, drowsiness, seizure or focal signs. These are rare but time-critical, and they are more common in children and adolescents.⁶

Lower airway

Chronic rhinosinusitis and asthma are the same inflamed airway at two levels. Sinus disease is associated with worse asthma control and more exacerbations, and treating the sinuses improves asthma symptoms and reduces oral steroid use. Chronic rhinosinusitis is also common in bronchiectasis, where both reflect one underlying disorder of clearance or immunity — which makes the upper airway part of respiratory management, not a separate specialty.⁷

Underlying immune and ciliary disorders

Recurrent or refractory sinusitis is one of the commonest presentations of antibody deficiency, and of primary ciliary dyskinesia and cystic fibrosis. Persistent sinus disease with recurrent chest or ear infection deserves an immune and ciliary workup rather than another antibiotic course.²

Sleep, fatigue and mental health

Chronic rhinosinusitis reduces quality of life by an amount comparable to other established chronic diseases, mainly through fatigue, sleep disruption, impaired concentration and reduced productivity. Depression and anxiety are more common in this group, and fatigue is often the symptom patients rank as most disabling — a point worth acknowledging explicitly, since it is rarely what gets treated.¹

Teeth, eyes and ears

Maxillary disease refers pain to the upper teeth, and dental infection can cause sinusitis in the other direction. Ethmoid disease refers pain behind and between the eyes, and eustachian tube dysfunction produces ear fullness and hearing change — all reflections of shared anatomy rather than separate problems.

Living with sinusitis

The daily routine

In chronic disease, saline rinsing and topical corticosteroid are long-term daily habits. Linking them to fixed points in the day is what makes them last, and a symptom score reviewed over months is a better guide to progress than day-to-day impressions.

Home and work environment

Humidity control and treatment of visible mould matter in coastal Queensland; dust, smoke and fumes aggravate the mucosa; and smoking is directly ciliotoxic, making cessation one of the highest-value interventions available. Where exposure is occupational, controls and respiratory protection are part of treatment.

Flying, diving and altitude

Pressure change across a blocked ostium causes pain and can cause barotrauma. Flying with an acute episode is best avoided; where it is unavoidable, saline, a topical decongestant before descent and slow equalising manoeuvres help. Diving should be deferred until the nose is clear.

Sleep

Nasal obstruction fragments sleep and drives mouth breathing. Evening saline and topical corticosteroid, a slightly elevated head of bed, and treatment of coexisting rhinitis all help — and where snoring or witnessed apnoeas are present, sleep apnoea should be assessed rather than assumed.

Exercise

Exercise is beneficial and should continue. Nasal obstruction pushes people to mouth breathing, which worsens exercise-induced symptoms in asthma; treating the nose is part of treating the chest. Chlorinated pools aggravate symptoms in some people.

Prognosis

Acute rhinosinusitis resolves without antibiotics in the great majority of people, usually within seven to ten days, and complications are rare but serious.⁵ Chronic rhinosinusitis is a long-term relapsing condition: most people achieve good control with sustained saline and topical corticosteroid, and surgery produces substantial improvement in symptoms and quality of life in those who fail medical treatment, with topical therapy continuing afterwards to maintain the result.¹¹ Outcomes are worse with continued smoking, untreated asthma or rhinitis, unrecognised immunodeficiency, and — in the polyp subgroup — high eosinophil counts and NSAID sensitivity. The most avoidable pattern remains years of repeated antibiotics without a proper trial of anti-inflammatory treatment.¹

Role of the physiotherapist

Physiotherapy does not treat sinus inflammation, and the honest framing matters: nothing in manual therapy or "sinus drainage" massage alters the disease. What the physiotherapist contributes is real and largely unclaimed by anyone else. It is teaching high-volume saline rinsing and nasal spray technique properly, with the device in the patient's hand — technique being the most common reason effective treatment appears not to work.⁹ It is breathing pattern assessment and retraining, restoring nasal, diaphragmatic breathing after prolonged obstruction and mouth breathing, and distinguishing sinus-related fatigue and breathlessness from deconditioning, asthma and dysfunctional breathing. It is checking inhaler technique and looking for the asthma that so often accompanies chronic sinus disease, and providing airway clearance where bronchiectasis, cystic fibrosis or primary ciliary dyskinesia sits underneath both. And it is knowing the warning signs of orbital and intracranial spread well enough to redirect a patient immediately rather than treat them.⁶

Part 1 · References

1. Fokkens WJ, Lund VJ, Hopkins C, et al. European Position Paper on Rhinosinusitis and Nasal Polyps 2020. Rhinology 2020;58(Suppl S29):1–464.
2. Orlandi RR, Kingdom TT, Smith TL, et al. International consensus statement on allergy and rhinology: rhinosinusitis 2021. Int Forum Allergy Rhinol 2021;11(3):213–739.
3. Rosenfeld RM, Piccirillo JF, Chandrasekhar SS, et al. Clinical practice guideline (update): adult sinusitis. Otolaryngol Head Neck Surg 2015;152(2 Suppl):S1–S39.
4. Therapeutic Guidelines Limited. Acute rhinosinusitis. In: Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Ltd, 2024.
5. Lemiengre MB, van Driel ML, Merenstein D, Liira H, Mäkelä M, De Sutter AIM. Antibiotics for acute rhinosinusitis in adults. Cochrane Database Syst Rev 2018;9:CD006089.
6. Hoxworth JM, Glastonbury CM. Orbital and intracranial complications of acute sinusitis. Neuroimaging Clin N Am 2010;20(4):511–526.
7. Global Initiative for Asthma. Global strategy for asthma management and prevention: 2026 update. GINA, 2026.
8. Chong LY, Head K, Hopkins C, Philpott C, Burton MJ, Schilder AGM. Saline irrigation for chronic rhinosinusitis. Cochrane Database Syst Rev 2016;4:CD011995.
9. Chong LY, Head K, Hopkins C, et al. Intranasal steroids versus placebo or no intervention for chronic rhinosinusitis. Cochrane Database Syst Rev 2016;4:CD011996.
10. Head K, Chong LY, Hopkins C, Philpott C, Burton MJ, Schilder AGM. Short-course oral steroids as an adjunct therapy for chronic rhinosinusitis. Cochrane Database Syst Rev 2016;4:CD011992.
11. Rimmer J, Fokkens W, Chong LY, Mendes C. Surgical versus medical interventions for chronic rhinosinusitis with nasal polyps. Cochrane Database Syst Rev 2014;12:CD006991.

References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.