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Sinusitis: Overview

Created: ; Last Update: October 18, 2018; Next update: 2021.


Sinusitis is an inflammation of the paranasal sinuses. The full medical term for sinusitis is "rhinosinusitis" ("rhino-" meaning "nose"), because it affects the mucous membranes lining both the nose and the sinuses.

The paranasal sinuses are part of the upper airways, and are connected to the nasal cavity. They are made up of several cavities in the skull found from the forehead down to the teeth of the upper jaw. Depending on where they are, these cavities are known as the frontal sinuses, the sphenoid sinus, the ethmoid cells and the maxillary sinuses. The paranasal sinuses are lined with mucous membranes that have tiny hairs on them (ciliated epithelium). These mucous membranes produce a secretion that runs down through the nose and throat.

Illustration: Position of the sinuses – as described in the article

Sinusitis can be acute or chronic: The acute form may appear several times a year, but it always goes away within several weeks at the latest. In chronic sinusitis, the mucous membranes lining the paranasal sinuses are inflamed for a longer period of time. Sinusitis is commonly considered to be chronic if the symptoms continue for more than three months.


Sinusitis often has the following typical symptoms:

  • Stuffy nose
  • Coughing
  • Fever
  • Pain
  • Swelling
  • A build-up of pus

If you have sinusitis, your nasal passages will become blocked due to the swelling and build-up of fluid. This makes it more difficult to breathe through the nose, which feels stuffy. A yellowish or greenish discharge is a sign of the presence of germs.

Sinusitis often causes pain in the forehead, the jaw and around the eyes and – less commonly – toothache. The pain and stuffy feeling usually get worse when you lean forward, for example when getting up out of bed. Your sense of smell is often affected, and you may lose it completely.


Acute sinusitis is often brought on by a cold or the flu. Colds are usually caused by respiratory viruses, and only rarely by bacteria. A bacterial attack, however, may occur in addition to a viral infection.

Viruses or bacteria trigger an inflammation, which causes the mucous membranes to swell up. This may keep fluid from draining from the sinuses. If that happens, the fluid becomes thicker and the sinuses fill up with thick, often yellow-green mucus. Allergies, nasal polyps, a deviated nasal septum (where the wall between the two nostrils is bent to one side) or a weakened immune system can all make sinusitis more likely.

It is often not known what exactly has caused chronic sinusitis. Sometimes it develops from acute sinusitis that has not cleared up properly. But there are other factors that can make chronic sinusitis more likely or make it worse:

  • Immune system disorders, for example hay fever or other allergies
  • Deviated nasal septum (where the wall between the two nostrils is bent to one side) or other abnormalities in or near the nose
  • Intolerance of acetylsalicylic acid (ASA – the drug in Aspirin)

Enlarged polyps constrict the nasal cavities, preventing proper ventilation. This makes it easier for germs to grow. Environmental factors like chemicals or cigarette smoke are thought to play a role as well.


If acute sinusitis doesn’t clear up properly, it can become chronic. One effect of chronic sinusitis can be mucous membrane growths called nasal polyps. They make it more difficult to breathe through your nose and can impair your sense of smell.

In very rare cases, the inflammation may spread to nearby parts of the body, like the eyes or brain. Signs of this more serious form of sinusitis include a high fever, swelling around the eyes, inflamed and reddened skin, severe facial pain, sensitivity to light and a stiff neck. If you have these symptoms, it’s important to seek medical advice immediately.


Your doctor will first ask about symptoms such as pain, fever, coughing, coughed-up phlegm and loss of smell, and about your general wellbeing. He or she will then perform a series of examinations. A tube-like device with a small lamp on it (endoscope) can be used to take a closer look at the inside of your nose and see whether the membranes are swollen and what color the secretions are. In rare cases, a sample of the secretions is taken and tested for germs in a lab. This is done by inserting a probe into the nose. Computed tomography (CT) or ultrasound can be used if a sample is not enough to provide a clear diagnosis or if there are signs of complications.

Finding out whether sinusitis is caused by bacteria or viruses can be quite involved. It often doesn’t make any difference in acute sinusitis because it hardly influences the treatment or course of the illness. Acute sinusitis usually clears up within one or two weeks.

An allergy test can help in chronic sinusitis, which is commonly associated with allergies.


Steroid nasal sprays may relieve the symptoms of sinusitis. Decongestant nasal sprays help over the short term at most, and should only be used for a few days. A nasal rinse or inhalation may also help, and antibiotics are an option in some cases.

In chronic sinusitis, one common treatment is a surgical procedure for expanding restricted passageways in the paranasal sinuses. This is an option if other treatments haven’t provided enough relief.

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment, and what to remember.


© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK279485


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