A viral infection
About 98% of acute sinusitis is caused by viruses, often during a cold.1
Inflammation can cause significant congestion and thick secretions, even without a bacterial infection.
Health education · InfectionsCare and treatments
Sinusitis: understanding the causes, symptoms and treatments
Stuffy nose, facial pressure, thick secretions or a reduced sense of smell: these symptoms can come with sinusitis. But sinusitis is not necessarily bacterial and does not automatically require antibiotics.1,2
How the symptoms evolve, how long they last and how severe they are help guide the assessment.
The sinuses
What is sinusitis?
The sinuses are hollow spaces in the facial bones, around the nose.5 Their lining makes mucus that normally drains into the nasal passages.
When this lining becomes inflamed and swollen, mucus may not drain as well. Secretions build up and a feeling of congestion or pressure can appear.
The term rhinosinusitis is also used, since the nose and sinuses are usually affected together.4
Causes
What are the causes?
A bacterial infection
It is less common.1,5 It becomes more likely when symptoms persist without improvement, are especially severe or get worse after first improving.1
Other factors
Allergies, tobacco smoke and other irritants, nasal polyps and, less often, a dental infection can contribute to sinus problems, especially when they persist or come back.5,6
Coloured mucus alone is not enough to confirm a bacterial infection.1 Chronic sinusitis is therefore not simply a cold that needs antibiotics for longer.
Symptoms
What are the symptoms?
Pain can be felt in the cheeks, forehead, around or between the eyes, depending on the sinuses affected.5
Duration
How long can symptoms last?
Viral rhinosinusitis, like a cold, usually lasts 7 to 10 days.4
There is no need to wait ten days if your condition is worrying or getting worse quickly. These guideposts guide the assessment; they do not let you diagnose yourself.
A bacterial infection becomes more likely, and an assessment is indicated, when symptoms:1
- persist for 10 days or more without improvement;
- improve, then suddenly get worse;
- are severe from the start, with a high fever (39 °C or more) and pus-like discharge or facial pain for 3 to 4 days.
Diagnosis
How is the diagnosis made?
The assessment is mainly based on the symptoms, their duration, their course and the clinical exam. The professional also checks whether another cause, such as an allergy or a dental problem, could explain the situation.2,4
Is an X-ray or a CT scan needed?
No, not for uncomplicated acute sinusitis.2,4,1 A sinus X-ray is not reliable enough to guide the diagnosis or the choice of antibiotic.2
A CT scan may be indicated if a complication is suspected, or to assess chronic sinusitis.2,4 A nasal swab is not recommended either.2
Relief
How to relieve the symptoms?
Relieving symptoms is the basis of treatment for viral sinusitis.2,1
Nasal rinsing
A saline solution, as a spray or rinse, helps clear secretions and relieve congestion.1,4
Rest and comfort
Warm compresses on the face can improve comfort.1 Rest and good hydration also help you feel better.
A pain reliever
Acetaminophen or ibuprofen, depending on age, medical history and contraindications.1 Ask a pharmacist, especially for a child, during pregnancy or with other illnesses.
A nasal corticosteroid
It reduces inflammation and may be enough to treat mild to moderate sinusitis.2,4
A decongestant, with caution
A decongestant spray works temporarily. Used for more than 3 days, it can make congestion worse (rebound effect).4,5
Nasal rinsing: use safe water
Health Canada recommends these precautions to reduce the risk of infection:3
- use distilled, sterile or boiled water: boil tap water vigorously for 3 to 5 minutes, then let it cool to lukewarm;
- store boiled water in a clean, closed container and use it within 24 hours;
- do not use tap water directly;
- bottled drinking water is not distilled or sterile water;
- clean the device according to the instructions and do not share it with anyone.
Antibiotics
When are antibiotics useful?
Antibiotics do not treat a viral infection and do not directly relieve symptoms.2
They may be indicated when the assessment points to a bacterial infection that needs treatment, for example if symptoms are severe or do not improve despite a trial of nasal corticosteroid.2
For a healthy person whose symptoms have lasted less than 10 days, a period of watchful waiting is reasonable. A delayed prescription may also be offered: the antibiotic is taken only if symptoms get worse within 2 to 3 days or do not improve in 5 to 7 days.1
Watching how things evolve does not mean leaving symptoms untreated: relief and reassessment are part of the treatment.
Complications
What complications can occur?
Serious complications are uncommon. An infection can, however, spread to the tissues around the eye or, more rarely, to the tissues around the brain.5,4 That is why some symptoms need urgent assessment.
When should you go to the emergency room?
Seek care right away if there is:1,4,2
- swelling around an eye;
- reduced vision or a change in vision;
- a change in vision;
- a very severe headache;
- confusion, unusual drowsiness or a major decline in general condition.
In immediate danger, call 911. For guidance based on your symptoms, call Info-Santé at 811, option 1.
Chronic sinusitis
What if symptoms come back or persist?
Sinusitis is called chronic when it lasts more than 12 weeks, even with treatment.6,5 When acute sinusitis comes back 4 or more times in a year, it is called recurrent sinusitis.5 It deserves an assessment to look for the causes.
Depending on the situation, a specialist exam, a nasal endoscopy or a CT scan may be needed.4 Care may include nasal rinsing, a nasal corticosteroid and control of related factors, such as allergies or smoking.6
When to consult at the Clinique IPS du Palais?
Sinusitis is among the common health problems the clinic can assess, according to the applicable clinical criteria. A nurse practitioner can assess your symptoms, recommend the right relief treatments and determine whether an antibiotic is indicated, within the limits of her scope of practice.
Nasal congestion is also one of the examples of reasons for a teleconsultation at the clinic. If you have warning signs, go to the emergency room without waiting.
Sources
- Nova Scotia Health, Antimicrobial Stewardship. Acute Sinusitis (Respiratory). Reviewed January 2025, accessed October 29, 2026. nshealth.ca
- Choosing Wisely Canada, Canadian Society of Otolaryngology – Head and Neck Surgery. Otolaryngology – Rhinology. Updated December 2024, accessed October 29, 2026. choosingwiselycanada.org
- Health Canada. Dispositifs de rinçage nasal et risques d’infection (French version). September 11, 2024, accessed October 29, 2026. canada.ca
- Desrosiers M, et al. Canadian clinical practice guidelines for acute and chronic rhinosinusitis. Allergy, Asthma & Clinical Immunology, 2011;7:2, accessed October 29, 2026. cfpc.ca
- Fried MP. Sinusite, Merck Manual, consumer version (in French). Updated July 2025, accessed October 29, 2026. merckmanuals.com
- Centre de littératie en santé du CHUM. La sinusite chronique (sheet No. 1127, in French). 2023, accessed October 29, 2026. chumontreal.qc.ca
This sheet provides general information and does not replace an assessment by a health professional. Published October 29, 2026.