Sinusitis

Sinusitis, more accurately called rhinosinusitis, is inflammation of the lining of the nose and the sinuses, the air spaces in the bones of the face. It can mean a blocked nose, pressure across the cheeks or forehead, thick discharge and a smell that has gone flat. One word covers two quite different problems: a short illness that clears, and a long-running inflammatory condition that does not.

What sinusitis is, and what it is not

Acute rhinosinusitis comes on suddenly and lasts less than four weeks. Canadian guidelines note that up to two thirds of people with sinus symptoms have viral disease rather than bacterial infection, and that a common cold usually peaks around day three and starts to improve by day seven. That is why the timing of your symptoms carries as much weight as the symptoms themselves.

Chronic rhinosinusitis is a different condition wearing the same name. It is defined by symptoms and inflammation lasting more than 12 weeks, and it is divided into disease with nasal polyps and disease without them. It is not a cold that has overstayed. It is a persistent inflammatory condition of the airway, and it often travels with asthma and allergy: a 2025 CMAJ review estimates asthma in about 25% of people with chronic rhinosinusitis, roughly five times the rate in the general public.

Signs and symptoms

• A blocked or stuffy nose that does not clear
• Thick discharge from the nose, or mucus running down the back of the throat
• Pain, pressure or fullness in the face, around the cheeks, eyes or forehead
• A reduced or absent sense of smell, often with a change in taste
• Headache, aching in the upper teeth, or pressure in the ears
• Cough, often worse at night, and broken sleep
• Tiredness, and in acute infection sometimes fever

Acute episodes tend to build and then fade over days. Chronic disease is steadier, with symptoms that sit in the background for months and flare from time to time.

What raises the risk

Some things cannot be changed:

• Structural differences inside the nose, such as a deviated septum, and nasal polyps
• Allergy and asthma, with asthma estimated in about 25% of people with chronic rhinosinusitis
• Genetic predisposition, which the CMAJ review lists among contributing factors alongside microbes and the environment
• Being female and getting older. Canadian survey data found self-reported rhinosinusitis in 5.7% of women and 3.4% of men, with prevalence rising with age up to about 60

Others can often be worked on, usually with support from a health care team:

• Smoking, which went with higher rhinosinusitis prevalence in both women and men in the Canadian survey data, and with higher prevalence in a 2025 global review
• Repeated viral upper respiratory infections, which is how most acute episodes begin
• Long use of over-the-counter decongestant nose sprays. Choosing Wisely Canada notes that using them for more than about three days can bring on rebound congestion

How sinusitis is diagnosed in Canada

Acute rhinosinusitis is usually identified by a family doctor or nurse practitioner from the pattern and duration of symptoms. Canadian guidelines use a check known as PODS: facial Pain, pressure or fullness, nasal Obstruction, nasal Discharge or discoloured postnasal drip, and Smell disturbance. Chronic rhinosinusitis is assessed differently. Canadian criteria call for symptoms lasting more than 12 weeks together with objective evidence of inflammation, found either by looking inside the nose with anterior rhinoscopy or a nasal endoscope, or as thickening of the sinus lining on CT. The 2025 CMAJ review notes that plain X-rays lack sensitivity and are not used for this. Referral to an otolaryngologist is used when symptoms are on one side only, when the picture is unclear, or when treatment has not brought the problem under control.

Treatment and day-to-day management

Clinical research for Sinusitis is enrolling. See the current studies ↓

Care depends on which of the two conditions is in front of you. For a short viral illness the aim is comfort while it settles; for chronic disease it is long-term control of inflammation. Depending on your situation, a health care team may discuss:

• Saline sprays and nasal rinses, described in Canadian guidance as a basic measure in both acute and chronic disease
• Intranasal corticosteroid sprays, which Canadian guidelines describe as the long-term mainstay in chronic rhinosinusitis and as single-agent treatment for mild and moderate acute bacterial rhinosinusitis
• Antibiotics, which Canadian guidance reserves for a minority of acute cases: where symptoms persist without improving, improve and then clearly worsen again, or are severe from the start. Choosing Wisely Canada notes that about one in four people who take antibiotics have side effects such as stomach problems, dizziness or rashes
• Biologic medicines for severe chronic rhinosinusitis with nasal polyps that has not responded to standard care. Dupilumab, mepolizumab and omalizumab are approved in Canada for this group
• Endoscopic sinus surgery, considered when medical treatment has not controlled chronic disease. The CMAJ review estimates that 10% to 30% of people go on to need revision surgery

Which of these applies, and when, depends on the type of sinusitis and on your own history. These are decisions for you and your own clinician, and this page is not a recommendation about any of them.

When to talk to a doctor

• Swelling or redness around an eye, a bulging eye, double vision or any change in vision needs assessment the same day. Go to an emergency department or call 911, because infection can spread from the sinuses into the eye socket.
• A severe headache with a stiff neck, confusion, drowsiness or a high fever needs emergency assessment, because these can signal spread to the lining of the brain.
• Book an appointment if acute symptoms last more than about 10 days without improving, if they improve and then clearly worsen again, if symptoms are on one side only, or if you have repeated nosebleeds.

Why clinical research matters for sinusitis

Both halves of this condition have unfinished business. On the acute side, Canadian prescribing has barely shifted: 84% of outpatient diagnoses of acute rhinosinusitis came with an antibiotic in 2013, compared with 87% in 2007, even though most episodes are viral. The authors of that study called for work to understand how the diagnosis is actually made in practice and what criteria drive treatment. On the chronic side, even the size of the problem is unsettled. Alberta physician claims gave 18.8 to 23.3 per 1,000 people, older Canadian survey data gave 5.7% of women and 3.4% of men, and a 2025 global review put pooled prevalence at 8.71%. Those figures cannot all be measuring the same thing. Research is now moving toward sorting chronic rhinosinusitis by the type of inflammation driving it, its endotype, rather than by whether polyps can be seen, because type 2, non-type 2 and mixed patterns appear to behave differently. Studies are testing biologic medicines aimed at specific inflammatory pathways, including phase 3 work on tezepelumab in severe disease with polyps, hunting for biomarkers that predict who responds, comparing medical treatment with surgery, and examining environmental contributors such as fine particulate air pollution.

Clinical studies are how those questions get answered. Taking part is voluntary, you give informed consent before anything begins, and you can stop at any time without affecting the care you get from your own doctor. Joining a study does not mean giving up your current treatment, and no one can say in advance whether a study will help you personally.

Learn more from Canadian sources

• Choosing Wisely Canada: treating sinus infections
• HealthLink BC: sinusitis
• Canadian Society of Otolaryngology Head and Neck Surgery: public information sheets
• CMAJ: diagnosis and management of chronic rhinosinusitis