Allergy, Nose & Sinus

Sinusitis: A Complete Guide By An ENT Specialist

blog-img Medically reviewed by Dr Gan Eng Cern, MBBS, MRCS (Edin), MMed (ORL), FAMS

Overview of Sinusitis

Sinusitis is the inflammation or swelling of the sinuses that surround your nose, usually caused by a viral or bacterial infection. It is a common condition that often clears up without medical treatment. However, if your symptoms last for more than 7-10 days or if you experience fever or a bad headache, you should schedule an appointment with your General Practitioner (doctor).

What are Sinuses?

Sinuses are small, air-filled spaces located in your facial bones that are connected to your nasal cavity or the inside of your nose. Since they surround the nose, they are also known as paranasal sinuses.

Everyone has 4 pairs of sinuses: behind your forehead (frontal sinuses), cheeks (maxillary sinuses), nasal bones (sphenoid sinuses) and between your eyes (ethmoid sinuses).

The main function of these sinuses is to produce mucus – a thin, watery fluid – that flows freely from your sinuses into your nasal cavity. This layer of mucus acts as a trap for dust, germs and other particles in the air. It also contains antibodies and bacteria-killing enzymes that help fight infections.

What is Sinusitis?

Sinusitis, or sinus infection, occurs when excess mucus builds up in your sinuses.

The presence of bacteria, viruses or allergens in your sinuses can cause too much mucus to form, blocking the tiny openings of your sinuses. As a result, mucus is unable to flow through these openings into the nasal cavity. The buildup of mucus in the sinuses encourages germs to grow, leading to a sinus infection.

Most sinus infections can clear up on its own without treatment. However, if your symptoms worsen after 5 days or persist longer than 10 days, a bacterial infection may be present and you should consult your doctor. Occasionally, an infected tooth or fungal infection can also cause sinusitis.

Healthy Sinus

Types of sinusitis

Sinusitis can be classified into 3 different types based on its duration.

Acute Sinusitis

Acute sinusitis is the most common type. A viral infection can cause symptoms that last between 1-2 weeks. In the case of bacterial infection, acute sinusitis can last up to 4 weeks.

Subacute Sinusitis

Subacute sinusitis symptoms last longer than acute sinusitis symptoms, between 4-12 weeks. This type commonly occurs with bacterial infections or seasonal allergies.

Chronic Sinusitis

Chronic sinusitis symptoms persist for more than 12 weeks and may continually return. This type is usually caused by bacterial infections, persistent allergies or structural nasal problems. It may also require more invasive treatment such as surgery.

Symptoms of Sinusitis

Symptoms of Sinusitis


Symptoms of sinusitis vary according to the length and severity of the sinus infection.

In general, if you have 2 or more of the following symptoms accompanied by thick, green or yellow nasal discharge, your doctor may diagnose you with sinusitis.

Common symptoms include:

  • Blocked or runny nose
  • Postnasal drip or mucus running down the back of your throat causing irritation
  • Thick nasal discharge
  • Reduced sense of smell and taste
  • Cough or congestion
  • Pain and tenderness around your cheeks, eyes or forehead

Other symptoms may include:

  • Pain in the upper jaw and/or teeth
  • Bad breath
  • Fatigue
  • Fever
  • Headaches
  • Nausea

When should you see your doctor?

If your symptoms are mild and improving, you don’t usually need to see your doctor and can look after yourself at home.

However, see your doctor if:

  • Your symptoms are severe or getting worse Eg.
    • Fever (above 39 degree celsius)
    • Swelling around your eyes or forehead
    • Severe headache or facial pain that does not resolve with over-the-counter (OTC) drugs
    • Confusion
    • Double vision or other visual disturbances
    • Stiff neck
  • Your symptoms persist after 7-10 days
  • Your symptoms continue after taking antibiotics prescribed by your doctor
  • You experience episodes of sinusitis frequently

Risk factors

The following may increase your risk of developing sinusitis:

  • Previous respiratory tract infections such as the common cold
  • Allergic reaction to substances such as dust, pollen or animal hair
  • Deviated nasal septum: a crooked septum (the wall between the nostrils) may restrict or block sinus passages, making the symptoms of sinusitis worse
  • Nasal polyps: small growths that can block nasal cavity or sinuses
  • Asthma
  • Dental infections
  • Immune system disorders or autoimmune diseases such as HIV/AIDS or cystic fibrosis that can lead to nasal blockage
  • Allergic rhinitis (hay fever)
  • Smoking
  • Regular exposure to pollutants such as carbon monoxide, nitrogen oxide, sulphur dioxide or secondhand cigarette smoke

Is Sinusitis contagious?

Sinusitis itself is not contagious. However, it often follows a cold which can spread to family members and friends.

How is it diagnosed?

Sinusitis can be diagnosed by the following methods.

Physical examination

To diagnose a sinus infection, your doctor will ask you about your symptoms and do a physical examination.

They may gently press a finger against your forehead and cheeks (over your sinuses) to check for pressure and tenderness. They may also examine the inside of your nose with a light source to identify inflammation, nasal polyps or other abnormalities.

However, if your symptoms persist, your doctor may refer you to an ENT specialist for further examination.

Using nasal endoscopy

Your ENT specialist may perform nasal endoscopy – a procedure to take a closer look at the nasal and sinus passages.

During the procedure, an endoscope (a small, thin and flexible tube with a light and camera attached) will be inserted into your nose and be guided through your nasal and sinus passages.

Detailed images of the areas will be visible through the endoscope. A sample may also be obtained for culture testing to test for the presence of an infection.

Imaging tests

In some cases, your doctor may order a CT scan or MRI to determine if there is mucus blockage or any abnormal structures such as polyps in your nasal passages and sinuses.

Other tests

An allergy test identifies irritants that may cause an allergic reaction.

A blood test checks for diseases that weaken the immune system such as HIV.


Treatment options vary depending on how long the symptoms last.

Over-the-counter (OTC) medications

Nasal decongestant drops or sprays: help relieve symptoms in the short run. However, don’t take them for longer than recommended (not > 5 days). Longer use can result in a rebound effect, making nasal congestion worse. Oral decongestants are not recommended for people with high blood pressure, prostate issues, glaucoma or sleep difficulties.

Pain relievers such as ibuprofen and acetamin: helps reduce pain such as headaches or pressure in your forehead and cheeks.

Check with your doctor before taking any of these medications to ensure they are the best choice for your symptoms.


In general, acute viral or early bacterial sinusitis may resolve without antibiotics. However, if your symptoms are more severe, your doctor may prescribe antibiotics.

Antibiotics help eliminate a sinus infection by attacking the bacteria that causes it, but until the drugs take effect, they do not do much to alleviate symptoms.

A typical course is usually between 7-21 days depending on your doctor’s instructions. Side effects include rashes, diarrhea or stomach issues.

Don’t stop taking your antibiotics earlier than instructed as this can allow the bacterial infection to fester and not be fully resolved. On the other hand, the overuse of antibiotics can lead to superbugs, which are bacteria that cause serious infections and cannot be easily treated.

Your doctor may have you schedule another visit to monitor your condition.

Sinus rinse

Sinus rinse is a salt water or saline solution that helps flush out the mucus in your nasal cavity and sinuses.

It can be made at home by mixing 1 cup of prewarmed water with ½ teaspoon of table salt and ½ teaspoon of baking soda. Then, spray it into your nose using a nasal sprayer or pour it into your nose with a neti pot.

It is important to perform the rinse at least twice a day until your symptoms resolve.

Nasal corticosteroids

Nasal corticosteroids (nasal steroid sprays) are used to prevent and treat inflammation. They are also effective in shrinking and preventing the return of nasal polyps.

They are available over the counter or by prescription.

Your doctor may also direct you to rinse your nasal cavity with a saline solution mixed with a corticosteroid such as budesonide.

Oral corticosteroids

Oral corticosteroids are usually prescribed if you have nasal polyps or a severe case of sinusitis. They are typically only used to treat severe symptoms.


Antifungal drugs can be prescribed to treat a fungal infection but this is rarely needed.

Allergies can be treated with antihistamines or allergy shots. Avoiding exposure to allergens in general can reduce the occurrence of allergic sinusitis.


If you aren’t responding to the above treatments, your ENT specialist may opt to perform functional endoscopic sinus surgery (FESS).

FESS is usually performed under general anesthesia (when you’re asleep) and patients can often go home on the same day.

During the procedure, the surgeon will insert an endoscope into your nose. It is a thin tube with a lens at one end that magnifies the inside of your nose. It allows the surgeon to see the opening of your sinuses and insert small surgical instruments.

The surgeon will then either:

  • Remove any thin bony partitions or tissues such as nasal polyps that are blocking the affected sinus
  • Inflate a tiny balloon in the drainage passages from your sinuses to enlarge them before the balloon is deflated and removed (balloon catheter dilation)

Potential common side effects and risks of this procedure include temporary discomfort and crusting inside the nose, bleeding from the nose and infection. Ensure that you discuss the risks with your surgeon beforehand.

Treatment may still be required following surgery to prevent the return of sinusitis.

Take note that insurers may require patients to provide in-depth evidence to show that surgery is for sinusitis and not for cosmetic surgery (to improve the appearance of your nose).

Home remedies for sinusitis

The following remedies can reduce pain and unblock the sinuses to allow proper drainage:

  • Over-the-counter (OTC) medications
  • Sinus rinse
  • Inhale steam from a pan of warm water (with some drops of essential menthol or eucalyptus oil) to help unblock your sinuses
  • Apply a warm, damp cloth to your face and forehead several times a day to reduce the feeling of pain from sinus pressure
  • Stay hydrated to help thin the mucus
  • Avoid overexerting yourself and rest to help the symptoms pass
  • Use a humidifier in your bedroom to add moisture to the air

What happens if sinusitis is left untreated?

You will experience pain and discomfort until sinusitis clears up.

Although rare, a sinus infection may lead to serious complications such as:

  • Vision problems: if your sinus infection spreads to your eye socket, it can cause reduced vision or blindness that can be permanent
  • Meningitis: a life threatening infection that can cause brain and spinal cord damage
  • Osteomyelitis: a bone infection
  • Orbital cellulitis: an infection of the tissue surrounding the eyes

Sinus infections in children (for parents)

It is common for children to have allergies and be prone to infections in the nose and ears.


Particularly for children, things that can cause sinusitis include:

  • Cold or allergy symptoms that don’t improve within 14 days
  • High fever (above 39 degree celsius)
  • Thick, coloured mucus coming from the nose
  • Post-nasal drip which can cause bad breath, coughing, nausea or vomiting
  • Headaches
  • Earaches


Particularly for children, things that can cause sinusitis include:

  • Allergies
  • Illnesses from other children at daycare or school
  • Pacifiers
  • Bottle drinking while lying on the back
  • Secondhand smoke


See your child’s doctor to determine the best course of treatment for your child.

In general, be careful when giving over-the-counter (OTC) medicines to children. Don’t give OTC cough or cold medicines or decongestants to your children if they’re under 2 years of age.

Most children will fully recover from a sinus infection without antibiotics. Antibiotics are only used for severe cases of sinusitis or in children who have other complications because of sinusitis.

If your child doesn’t respond to treatments or develops chronic sinusitis, your doctor might recommend that they see an ear, nose and throat (ENT) specialist.

An ENT specialist will examine the sinuses more closely and look for any problems in the structure of the nasal passages that could be causing the sinus infection.

Surgery should always be the last resort on sinusitis in children, and obtaining a second opinion is recommended before proceeding.

Can sinusitis be prevented?

There is no guaranteed way to prevent sinusitis. However, to reduce your risk, you should:

  • Eat plenty of fruits and vegetables, which are rich in antioxidants and other chemicals, to boost your immune system and help your body resist infections
  • Practice good hand hygiene (wash your hands frequently with soap and water, especially before meals) and try not to touch your face
  • Avoid smoking and inhaling secondhand smoke: tobacco smoke can irritate and inflame your lungs and nasal passages
  • Keep your vaccinations up to date
  • Stay away from people with colds and other respiratory infections
  • Use a humidifier to moisten the air at home
  • Maintain your air conditioning units regularly in order to prevent mold and dust from collecting
  • Manage your allergies: work with your doctor to keep your symptoms under control and avoid exposure to things you’re allergic to whenever possible