Southern Cross Medical Library

Southern Cross Medical Library

Sinusitis is the infection or inflammation of the nasal sinuses causing congestion, pressure build-up, pain and other symptoms.

What are sinuses?

The nasal sinuses are four pairs of air-filled cavities within the bones of the face — above and around the eyes and nose. They are connected by small openings to the nasal cavity (the area between the nostrils and the back of the throat, through which we breathe).

The sinuses are lined with mucous membranes that produce slippery fluid called mucus, which helps to remove dust, bacteria, and other air pollutants from the sinuses and nasal cavity. In healthy sinuses, air passes in and out of the sinuses and mucus drains into the back of the nasal cavity.


Any condition that prevents the flow of air into, and drainage of mucus out of, the sinuses can lead to sinusitis. Most often the condition is caused by infection but it can also be the result of an allergic reaction. Sinusitis can be acute (short-lasting) or chronic (long-term).

Sinusitis is usually caused by infection, although swelling from allergies can mimic the symptoms of pressure, pain, and congestion. Usually the infection that causes sinusitis is bacterial, though viral and fungal infections can also cause the condition.

Obstructions within the nasal cavity or sinuses such as when the partition between the nostrils is off-centre (deviated septum) or nasal polyps (small growths on the mucous membrane) can lead to sinusitis by preventing the drainage of mucus and creating a breeding ground for infection.

The following may increase the risk of sinusitis:

  • Upper respiratory airways infection (eg: a cold or flu)
  • Dental infection
  • Cystic fibrosis
  • Weakened immune system (eg: due to chemotherapy)
  • A change in atmospheric pressure (eg: air travel or scuba diving)
  • Smoking and other air pollutants.

Signs and symptoms

One of the most common symptoms of sinusitis is pain, and the location of that pain depends on which sinus is affected. The pain may be worsened by bending, coughing, or sneezing. Other symptoms may include:

  • Nasal congestion
  • Nasal discharge (which may be yellowish, greenish, or blood-stained if infection is present)
  • Post-nasal drainage (drainage of mucus down the back of the throat)
  • Sore throat
  • Fever
  • Fatigue
  • Decreased sense of smell
  • A general feeling of fullness of the face.

Chronic and acute sinusitis have similar signs and symptoms — the key distinction between them is their length of time you have the symptoms.

Acute sinusitis:

Acute sinusitis that’s caused by a cold or allergies like hay fever will usually clear up in a week or two. Acute sinusitis may sometimes clear up and, after a period of no symptoms, come back again.

Chronic sinusitis:

The transition to chronic sinusitis occurs when a patient has continuous symptoms for more than three months. The sinuses may become narrowed or closed completely due to chronic infection and inflammation. Ongoing allergies and environmental irritants (eg: cigarette smoke) may be a cause.


Diagnosis of sinusitis can be difficult as its symptoms can mimic those of a common cold. A doctor will discuss the nature and duration of symptoms, and perform a physical examination including looking in the ears, throat, and nose.

In recurrent and chronic cases, a referral to an ear, nose, and throat (ENT) specialist for additional investigation may be necessary.

These may include:

  • Examination of the nasal cavity and sinus openings with an endoscope (a small, thin telescope which enables the structures to be viewed through the telescope or on a TV monitor).
  • CT scan (specialised X-ray imaging that allows a cross-sectional view of the sinuses to be seen).
  • X-rays (less commonly used as CT scans give better resolution)
  • Allergy tests and nasal/sinus cultures to identify the allergen or bacteria causing the sinusitis.


Treatment aims to relieve symptoms and restore the normal flow of air and mucus through the sinuses.

Non-surgical treatment:

Antibiotics are used to treat bacterial infection. A 7- to 10-day course of medication is usually prescribed. Longer courses may be needed for cases of recurrent or chronic sinusitis.

Decongestants relieve nasal congestion by drying up the mucus. These can be in the form of tablets and nasal drops or sprays. Care must be taken as decongestants can excessively dry the nasal mucous membranes, which leads to further swelling and congestion. It is important to clearly follow the medication instructions when using nasal decongestants.

Corticosteroid medications such as prednisone may be prescribed, in conjunction with an extended course of antibiotics, to treat cases of chronic sinusitis. Corticosteroid nasal sprays may also be prescribed.

Other treatments that aim to relieve the symptoms include pain-relieving medications, such as paracetamol and ibuprofen, steam inhalers, saline nasal sprays, and the application of heat or cold packs to the area surrounding the sinuses. Drinking plenty of fluids helps to thin the mucus so that it drains more easily.

Avoiding allergens (allergy-producing irritants) and taking antihistamines medications to reduce allergic reactions may also prove effective. If allergies contribute to the sinusitis, treatment that gradually builds up immunity to allergens (desensitisation therapy) may be recommended.

Surgical treatment

Surgery may be recommended for cases of recurrent or chronic sinusitis where non-surgical treatment has not been effective. It aims to improve airflow and drainage between the sinuses and the nasal cavity by correcting structural abnormalities such as a deviated septum, removing obstructions such as polyps, and by removing areas of diseased tissue.

Endoscopic surgical techniques have largely replaced conventional open surgery for sinusitis in New Zealand. Open surgery is used mainly in the treatment of seriously damaged sinuses or to allow areas not easily reached by an endoscope to be treated.

Endoscopic sinus surgery is usually a day-stay procedure performed under either a general anaesthetic or a local anaesthetic with sedation. The endoscope allows the surgeon to easily see the inside of nasal cavity and into the sinus openings. The surgery can be performed with minimal damage to healthy tissue.

There is usually only minimal pain after the surgery and this may be treated with pain-relieving medications such as paracetamol. Antibiotics may be prescribed to prevent post-operative infection and nasal sprays may be prescribed to flush out debris and promote healing.

The surgeon will give recovery and activity guidelines before the patient goes home. It is usually advised to take some time off work; avoid exercise, strenuous activity, and bending; and not to blow the nose for a period.


Preventing sinusitis may be possible during a cold or when allergies are problematic by:

  • Treating the allergy promptly
  • Drinking plenty of fluid to help thin nasal mucus
  • Gently blowing the nose, one nostril at a time, rather than sniffing
  • Regularly washing hands with soap and water
  • Using an oral decongestant or nasal decongestant spray — being careful to follow the instructions for use closely
  • Avoiding allergy triggers
  • Get an influenza vaccine each year
  • Use a humidifier.


MedlinePlus (2018). Sinusitis (Web Page). Bethesda, MD: US National Library of Medicine (NIH). [Accessed: 17/09/20]
NHS (2017). Sinusitis (Web Page). Redditch: National Health Service (NHS) England. [Accessed: 17/09/20]
O’Toole, M.T. (Ed.) (2017). Sinusitis. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.

Last Reviewed: September 2020


Go to our Medical Library Index Page to find information on other medical conditions.

The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross.