When you suffer a sinus infection, doctors will refer to this as “sinusitis”, meaning your sinuses are inflamed. The cause of sinusitis can be an infection or may also occur from another problem such as allergies. Sinuses refer to the air spaces that are in the bones surrounding your nose. These are hollow spaces that produce a substance called mucus, which slowly drains into your nose.

These are normal air-filled spaces surrounding the nose. There are 4 big groups of sinuses which can be infected with pus resulting in sinusitis.

The 4 groups of sinuses serve several functions for us, such as warming up and humidifying air that is taken in, providing insulation of the surrounding structures such as the eyes and nerves that run within the skull. Structurally, they also may help to act as buffers against trauma.

Sinusitis refers to a sinus infection. Sinusitis (sinus infection) can generally happen in 2 forms: 

Acute Sinusitis (lasting under 3 months); or Chronic Sinusitis where patients have blocked nose and experience nasal discharge (runny nose) for more than 3 months. Severe sinus infections can result in a loss of smell (Anosmia). Symptoms include headaches, facial pain or eye pain. This is because the sinuses and nasal passages are located around the eyes.

Sinus picture - 4 big groups of nasal passages surrounding the nose.

Sinus picture – 4 big groups of nasal passages surrounding the nose.

Other symptoms of sinusitis include: 

  • Blocked nose
  • Runny nose & sneezing
  • Coloured mucus (nasal discharge)
  • Facial pain
  • Sinus headaches
  • Postnasal drip
  • Reduced sense of smell (Hyposmia or Anosmia)
  • Nose bleed (Epistaxis)
  • Bad breath

Below, I have listed are some of the causes that may lead to acute sinusitis or chronic sinusitis. 


Sinusitis caused by allergies happen when a substance your body identifies as an allergen causes the nasal passages to swell. The items that cause an allergic reaction differs for every person, but common items include: pollen, mold, dust mites, pet hair. 

Allergies typically cause acute sinusitis. The symptoms only present themselves as you come into contact with the allergens. However, environmental factors could contribute to chronic sinusitis. For instance, if the patient is frequently in contact with the source of allergens, such as household pets, or mold in the living area. Usually, nasal sprays work well to alleviate symptoms of allergic sinusitis.

Bacterial Infection

Bacterial Infection happens when bacteria infects the lining of your nasal cavities and passages, thus causing sinusitis. Generally I would look for any of the following symptoms as signs of a bacterial infection as well: 

  1. If infection persists longer than 10 days without alleviation of symptoms or observable clinical improvement;
  2. Fever above 38.9˚C;
  3. Postnasal Drip is present;
  4. Symptoms progressively get worse after 5-6 days, instead of getting better.

Fungal Infection

Sinusitis caused by fungal infection is less common than the above types of sinusitis. Unless there are other conditions that compromise the immune system, such as diabetes, leukemia, lymphoma or immunodeficiencies, our bodies are typically able to ward off fungal infections quite easily. Medications that suppress the immune system may encourage fungal infections too.

Symptoms of fungal sinusitis are largely similar to other forms of sinusitis. However, in an individual with a compromised immune system, the sinusitis symptoms experienced can be more severe, such as pain or numbness in the facial regions, swelling of cheeks and/or eyelids, or even colour changes in the skin.

In very rare cases, the sinus infection can spread from the nasal passages to the brain. Complications and conditions such as meningitis –an inflammation of the lining that surrounds the brain— may arise.

Symptoms of sinusitis can be easily confused with symptoms of the common cold. Many people expect it to go away on its own. I would advise those who experience persistent sinusitis symptoms over a week, especially if they progressively get worse or experience a fever to see a doctor for a professional evaluation.

Evaluation involves a thorough examination by Dr Dennis Chua. A gentle nasoendoscopy is done to assess the patient’s condition. You may or may not require a CT scan of the sinus for further assessment.

A thorough nasoendoscopy can reveal mucopus with postnasal drip. This resulted in the patient experiencing symptoms like sore throat and chronic cough with minimal nasal symptoms since the pus was irritating the throat more than the nose.

Treatment usually involves nasal wash with nasal sprays. Antibiotics may be needed to treat the sinus infections, but will only work provided if the cause is not bacterial. If the sinus infection persists after a course of broad-spectrum antibiotics, a swab of the pus from the sinuses may be needed to assess and determine a suitable targeted antibiotic therapy.

Endoscopic Picture of a swab of the pus from the sinuses

Endoscopic Picture of a swab of the pus from the sinuses. This is to find out the organisms causing the sinus infections and to help determine the antibiotic therapy suitable to treat this infection.

In severe cases where the sinus infection causes the nasal passages to be blocked and the pus is unable to be drained, minimally invasive techniques like a balloon sinuplasty can be used to wash out the pus out of the sinuses. No incisions on the face are necessary for this operation. Everything is performed endoscopically within the nose.

Picture of endoscopic balloon sinuplasty

Picture of endoscopic balloon sinuplasty. The device is used to access the opening of the blocked sinuses and the balloon is inflated to “unblock” the sinuses for aeration.

Occasionally, patients who have failed maximal medical therapy may be required to undergo a Functional Endoscopic Sinus Surgery (FESS) to thoroughly wash out the sinuses. If nasal polyps are detected at the same time, they can be removed and sent for histology to exclude a tumour. This is usually a day surgery procedure with minimal discomfort to the patient.

For complex nose and sinus infections and diseases, Image Guidance System (IGS) is required during surgery. that Dr Dennis Chua is accredited to do this. The sinuses are located near critical structures like the eye and the brain. Accuracy and precision during surgery is necessary to ensure complete removal of diseased tissues and to minimize the chance of injury to the critical structures. Having IGS during surgery to treat sinus infection is akin to driving with GPS (navigation), it allows the use of sinus equipment to treat each of the diseased sinuses accurately.

  • There can be some blood-stained mucus discharge from the nose in the first 24 hours after surgery. This will lessen after that.
  • You may experience some nasal congestion due to the dressings applied by our ENT Specialist, Dr Dennis Chua, within the nose and sinus to expedite wound healing. This will be removed the following day.
  • The results of any histology sent (for example polyps) will take 3 working days for the final results to be out.
  • You may feel slightly giddy due to the anaesthetic effects. Be careful when you move about.
  • Do not agitate the wound in the nose and sinus by frequent throat or nose clearing. This can result in bleeding.
  • Be gentle around the nose and oral cavity. If you find a lot of mucus or phlegm in the throat, you can swallow it.
  • If you feel the urge to sneeze, do so with the mouth open. Sneezing results in airspeeds of up 150Kmh and can traumatise the wounds in the nose and sinuses.
  • Avoid straining or heavy lifting in the first 2 weeks after the operation. Intense physical exertion is not recommended.

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