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Sinusitis - causes, symptoms, treatment

Sinusitis is the inflammation of the lining of one or more of the nasal sinuses. The inflammation causes congestion, which leads to a build-up of pressure causing pain and other symptoms. 
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).


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 to the nasal cavity (ie: the area between the nostrils and the back of the throat, through which we breathe) by small openings.

The sinuses are lined with the same kind of mucous membrane that lines the rest of the respiratory system. In healthy sinuses, air passes in and out of the sinuses and mucus produced by the mucous membrane is able to drain into the back of the nasal cavity. Mucus helps to remove dust, bacteria and other air pollutants from the sinuses and nasal cavity.

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 a crooked partition between the nostrils (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)
  • Allergy and related conditions (eg: asthma, hay fever)
  • Dental infection
  • A change in atmospheric pressure (eg: air travel or underwater swimming
  • Smoking and other air pollutants.

Signs and symptoms

When inflammation, swelling and/or obstruction within the sinuses prevents drainage and causes mucus to build up, congestion occurs. Because the sinuses are unable to drain, this congestion leads to increased pressure in the sinuses.

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
  • Bad breath
  • Headache
  • Earache
  • 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 duration. 

Acute sinusitis:  
Acute sinusitis is when symptoms last up to four weeks, and commonly occurs as the result of a cold, a bacterial or viral nasal infection, or as a result of allergies.  There may be repeat occurrences, eg: after a cold, but symptoms are absent between occurrences. 

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 causative factor.


Diagnosis of sinusitis can be difficult as its symptoms can mimic those of a common cold. In order to make an accurate diagnosis the doctor will take a full medical history including an assessment of the nature and duration of symptoms. They will also perform a physical examination including looking in the ears, throat and nose.

In recurrent and chronic cases a referral to a specialist ear nose and throat surgeon (otolaryngologist) may be required, as more extensive diagnostic procedures 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 television monitor).
  • A CT scan (a specialised x-ray that allows a cross sectional view of the sinuses to be seen, also called a “CT Miniseries”).
  • 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 mucous 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 mucous.  These can be in the form of nasal drops or sprays, or can be taken in tablet form.  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, in order to treat cases of chronic sinusitis.  Steroid nasal sprays may also be prescribed.
Other treatments that aim to relieve the symptoms include pain-relieving medications, steam inhalers, saline nasal sprays and the application of heat or cold packs to the area surrounding the sinuses.  Avoiding allergens (allergy-producing irritants) and taking antihistamines to reduce allergic reactions may also prove effective. If allergies contribute to the sinusitis, immunotherapy may help to prevent recurrences.
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 post-operatively 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 of time. 


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

  • Drinking plenty of fluid - this helps to thin the nasal mucus so it drains more easily
  • 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
  • Quit smoking and avoid polluted air
  • Use a humidifier.


MedlinePlus (2016). Sinusitis (Web Page). Bethesda, MD: US National Library of Medicine (NIH). [Accessed: 15/08/17]
NHS Choices (2015). Sinusitis (Web Page). Redditch: National Health Service (NHS) England. [Accessed: 15/08/17]
O’Toole, M.T. (Ed.) (2013). Sinusitis. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis, MI: Elsevier Mosby.
Last Reviewed - August 2017


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