The sinuses are air-filled spaces in the bones of the face, connected to the nose by small openings. When their lining stays inflamed for more than 12 weeks, with a blocked nose or discharge and often pressure in the face or a poorer sense of smell, this is called chronic rhinosinusitis, or chronic sinusitis for short.
How it differs from a cold or acute sinusitis
A cold is a viral infection whose blocked, runny nose usually clears within a week or two. When the inflammation reaches the sinuses, with pain over the cheeks or forehead and thick discharge, it is called acute sinusitis, which is also usually caused by a virus and settles on its own within a few weeks.
Chronic sinusitis does not settle. Its main symptoms are a blocked nose, discharge from the nose or down the throat, a reduced or lost sense of smell, and pressure or pain in the face. In some people the inflamed lining forms nasal polyps, soft swellings that block the nose and the openings of the sinuses. The diagnosis rests on an examination, not on the symptoms alone.
Symptoms on one side of the nose only, swelling around the eye or a change in vision are not the usual pattern; UK guidance asks for them to be seen by an ENT specialist urgently.
The first treatments
Chronic sinusitis is treated with medicines first, and most people respond well. The usual start is salt-water rinses together with a steroid nasal spray or drops: the rinses wash out mucus and crusts, and the steroid reduces the swelling of the lining and shrinks polyps. Steroids used in the nose are not usually absorbed by the rest of the body. They work slowly, so they are used every day, and technique matters.
UK guidance describes a three-month trial of both before referral to a specialist. With polyps, a short course of steroid tablets may also be tried, weighed against their side effects. Antibiotics are not a routine treatment: the 2025 guideline of the American Academy of Otolaryngology–Head and Neck Surgery advises against them when no pus is seen in the nose.
How the nose is examined
The assessment starts with your symptoms: how long they have lasted, what you have tried and how they affect daily life. Asthma, allergies and sensitivity to aspirin are asked about too, as they often go together with chronic sinusitis, especially with polyps.
The central examination is nasal endoscopy: a thin camera, passed into the nostril after a numbing spray, shows the lining, any polyps or pus, and the septum. It takes a few minutes in the clinic.
A CT scan is not needed for everyone. It helps when the diagnosis is unclear, and it is needed before any sinus operation to show which sinuses are blocked and to map the anatomy near the eyes and the base of the skull.
When surgery is considered
Endoscopic sinus surgery is considered when endoscopy, a CT scan or both have confirmed the diagnosis, symptoms remain moderate or severe after a proper trial of medical treatment, and the likely benefits outweigh the risks for you. With mild symptoms, or health problems that make a general anaesthetic risky, an operation may not be the right way to help.
Some forms respond less well to medicines alone, such as extensive polyps or a fungal ball inside a sinus. The American guideline advises against requiring a fixed period of medication before surgery: the decision rests on your symptoms, the findings and the treatment already tried.
In a randomised trial at 20 UK hospitals, 514 adults whose symptoms persisted despite steroid sprays, saline rinses and a short course of antibiotics received surgery, three months of an antibiotic or a placebo, and all continued their sprays and rinses. At six months, the surgery group reported clearly fewer symptoms on a standard questionnaire, and the antibiotic did no better than the placebo. Results differ from person to person.
What the operation does
The operation, functional endoscopic sinus surgery (FESS), is done through the nostrils with an endoscope, a thin telescope connected to a screen, so there is no cut on the face. It is usually done under general anaesthetic, and most people go home the same day.
Its aim is to reopen the natural drainage pathways of the sinuses: swollen lining, polyps and small pieces of bone that block the openings are removed, the openings are widened and trapped mucus is drained. The sinuses themselves are not removed; once they can drain and air can move through them, the lining has a better chance to settle.
Which sinuses are opened depends on the CT scan and the findings. A deviated septum that narrows the way to the sinuses may be straightened at the same time.
Recovery in outline
The nose usually feels blocked for seven to ten days and then gradually improves; some bleeding and blood-stained discharge are normal at first. Packing, if used, is often the dissolving kind. A responsible adult should stay with you for 24 hours after the anaesthetic.
Do not blow your nose for two days after you get home, and then start gently. Saline rinses help clear crusts and lower the risk of infection; your surgeon will tell you when to start them. At follow-up visits the healing is checked, and crusts may be cleaned away.
Plan for up to two weeks off work, though some people go back sooner. For two weeks, avoid heavy lifting, running, exercise classes and heavy housework or gardening, and do not fly.
Risks of the operation
Most sinus operations go without complications, but every operation carries risks. The figures below come from ENT UK, the British association of ear, nose and throat surgeons:
- Bleeding: some is normal, and about 1 in 20 people have a heavier nosebleed.
- Infection, which may need antibiotics.
- Adhesions, bands of scar tissue inside the nose, which may need to be divided.
- A watery eye, in fewer than 1 in 100.
- Bleeding into the eye socket, in about 1 in 500, which can threaten the sight of that eye unless it is treated quickly; double vision and loss of vision are rarer.
- A leak of the fluid around the brain, in about 1 in 1,000, with a risk of meningitis.
- The general risks of an anaesthetic.
The effect on the sense of smell is hard to predict: it may improve partly, for a while, or not at all. Symptoms can also return over the years, polyps especially, and a second operation is sometimes needed.
After the operation, heavy bleeding that does not stop, swelling or pain around the eye, or a change in vision is an emergency: call 112. A fever that does not settle, increasing pain or clear watery fluid dripping from the nose should be reported to your surgeon the same day.
Treatment usually continues after surgery
Surgery opens the sinuses, but it does not change the tendency of the lining to become inflamed, so steroid sprays or drops and saline rinses usually continue afterwards, often for the long term; with the sinuses open, the spray reaches places it could not reach before. Polyps in particular tend to return if the steroid is stopped, even after an operation.
The result is usually assessed three to twelve months after surgery, from your symptoms and an endoscopy. Whether surgery suits you, and which treatment to try first, are questions answered at a consultation, once your nose has been examined.