What is sinusitis?

Sinusitis, also known as rhinosinusitis, describes inflammation and swelling of the sinus lining. Common symptoms of sinusitis include pain in the face, a blocked or runny nose, fever and headache. In most cases, symptoms develop quickly, within 1-2 days, and then clear within about 10 days. Less frequently, sinusitis can last for weeks or months.

The sinuses are hollow spaces located in the forehead (frontal), cheeks (maxillary), around the eyes (ethmoidal) and at the base of the skull (sphenoid). Mucus produced in the nose and sinuses provides a moist environment and helps to flush out bacteria. Together, these spaces also control the water content and temperature of that that passes down the windpipe and into the lungs.

Sinusitis usually starts with a viral infection of the nose and sinuses, such as during a cold. The build-up of mucus during these infections is often enough to trigger an inflammation of the sinus linings. However, sinusitis can also be caused by a separate infection with a bacteria or fungus, or by another unrelated factor, such as an allergy, medical condition or nose abnormality.

Although anyone can develop sinusitis, it tends to be more common in young children, the elderly and people with asthma or allergies. Some people develop sinusitis regularly with most colds, while others it affects only rarely.

The head of a man showing the position of the frontal, ethmoidal and maxillary sinsuses.The front and side view of the different sinuses. 

Allergy

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Signs and symptoms

Common signs and symptoms of sinusitis include:

  • Pain in the face, especially when leaning forward;
  • Tenderness or swelling in the face;
  • Pressure inside the head, especially around the forehead and eyes;
  • Yellow or green mucus in the nose;
  • Fever;
  • A blocked nose;
  • An ongoing cough;
  • Aching teeth and upper jaw;
  • A reduced sense of smell;
  • Bad breath (halitosis), and;
  • A feeling of being generally unwell.

Other signs of sinusitis in children may include restlessness, breathing through the mouth, a nasal voice and difficulty eating or feeding.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Causes

The nose and sinuses are lined with a thin layer of mucus that traps foreign substances, such as dirt, bacteria and pollution. Tiny hairs in this layer help to sweep the mucus to the back of the throat and down into the stomach. Sinusitis occurs when this normal flow is disrupted, causing a build-up of mucus in the sinuses.

The most common cause of extra mucus is a viral infection, such as during a cold. The mucus irritates the sinus linings, leading to the characteristic inflammation and swelling of sinusitis. Excess mucus is commonly thought to be the main reason for a blocked nose, but the actual cause is the narrowing of the nose and sinuses as a result of the inflammation. 

Three cross-sections of the face and sinuses showing the swelling, blocked drainage and infection that occurs in sinusitis.Sinusitis is characterised by infected sinuses that are swollen and blocked. 

In addition to viral infection, the sinuses can also become blocked by a range of other factors, including allergy, growths in the nose (nasal polyps), nose abnormalities or irritation from substances in the environment, such as smoke or pollution.

A build-up of mucus in the sinuses can also provide an ideal environment for other bacteria to grow. For this reason, a bacterial sinus infection can occur in a small number of cases, sometimes in addition to an initial viral infection. Bacteria most likely to cause sinusitis include Streptococcus pneumoniae, Haemophilus influenzae type B, and Moraxella catarrhalis.

In rare cases, sinusitis can also be caused by infection with a fungus, usually from the Aspergillus family. However, fungal sinusitis tends to mainly affect people who have a weakened immune system or an an underlying medical condition.

Allergy

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Nasal polyps

Fleshy outgrowths or lumps from the internal lining of the nose and sinus, often due to allergies, that can cause nasal obstruction and sinusitis.

Risk factors

Risk factors that increase the risk of developing sinusitis include:

  • Being prone to colds or the flu;
  • Having untreated allergies, such as hay fever (allergic rhinitis);
  • Having a damaged or crooked nose (deviated septum);
  • Asthma;
  • Growths inside the nose or sinuses (nasal polyps);
  • Exposure to irritating substances in the air, such as pollution or cigarette smoke;
  • Overuse of nasal decongestant sprays;
  • A tooth infection or abscess;
  • Changes in altitude from activities such as swimming, flying or scuba diving, and;
  • Certain medical conditions or treatments relating to HIV, gastric reflux, cystic fibrosis or chemotherapy.

Abscess

A swollen area of tissue containing a build-up of pus.

Allergies

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.

Chemotherapy

A medication-based treatment, usually used in the treatment of cancers. There are numerous, different types of chemotherapy drugs that can be prescribed by a specialist. These can commonly be used alongside other cancer treatments such as surgery and radiotherapy.

Gastric reflux

A condition in which stomach acid or contents come back up into the gullet, or oesophagus.

HIV

A virus transmitted mainly by sexual or blood-to-blood contact, that infects cells of the immune system. It is the causative agent of acquired immune deficiency syndrome (AIDS).

Nasal polyps

Fleshy outgrowths or lumps from the internal lining of the nose and sinus, often due to allergies, that can cause nasal obstruction and sinusitis.

Types

Sinusitis is often classified as either acute or chronic according to the following criteria:

  • Acute - symptoms last less than four weeks, or;
  • Chronic - symptoms last 12 weeks or more.

Acute sinusitis

Acute sinusitis usually follows a viral infection, such as during a cold or the flu. A small number of people will also become additionally infected with bacteria in the sinuses. In these cases, symptoms may be worse and last longer. However, acute sinusitis is often mild and clears without specific medical treatment.

Chronic sinusitis

In most cases, chronic sinusitis follows acute sinusitis. However, it can also be caused by other factors, such as an infected tooth, growths inside the nasal cavity (nasal polyps), damage to the nose or face, objects pushed into the nose, or an allergy such as hay fever. Generally though, chronic sinusitis is uncommon and tends to occur in people who have a weakened immune system or an underlying medical condition.

Allergy

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.

Nasal polyps

Fleshy outgrowths or lumps from the internal lining of the nose and sinus, often due to allergies, that can cause nasal obstruction and sinusitis.

Methods for diagnosis

Your doctor may diagnose sinusitis from a physical examination of your nose, in combination with assessment of your symptoms and medical history. In some cases, a sample of the mucus may be tested to determine cause of the infection. 

If you have chronic sinusitis, or previous treatments have not worked, your doctor may refer you to an ear, nose and throat (ENT) specialist. Further tests may include a blood test, computerised tomography scan (CT scan) or nasal endoscopy (nasendoscopy). 

Nasal endoscopy involves passing a thin tube, with a camera, through a nostril to enable a closer look at the sinuses. Local anaesthetic nasal spray is given before this procedure to reduce pain and discomfort.

Computerised tomography

A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Types of treatment

Most cases of sinusitis are short-term (acute) and tend to clear without treatment within 7-10 days. However, if the condition is long-term (chronic), or the symptoms are becoming worse, your doctor may recommend one or more of the following treatment options:

Self care

Breathing in steam from a bowl of hot water or shower may help to clear blocked sinuses. Similarly, flushing the nose and sinuses with salt water several times a day may also relieve some symptoms. Salt water sprays are available over the counter from a pharmacy, or may be prepared at home. Applying a hot compress to the face may also provide comfort.

These options may be particularly useful in children who are unable to take certain medications. Asking your doctor for advice on how to prepare and use these treatments is recommended.

Medications

Decongestants

Decongestant medications may provide short-term relief of sinusitis in some people. These medications open up a blocked nose by reducing inflammation and swelling of the mucous lining. Some examples include phenylephrine, pseudoephedrine, oxymetazoline, tramzoline and xylometazoline. These medications are available over the counter in a variety of forms, including oral tablets, nasal sprays and drops.

Side effects from nasal decongestants include a burning or stinging sensation in the nose and increased mucus production. Taking these medications for longer than five days, or at a higher-than-recommended dose, can cause constant blockage of the nose, unless the medication is repeatedly used. Also known as rebound congestion, this side effect can take weeks to improve. Nasal decongestants are not usually suitable for children under six years of age.

A man inhaling an intranasal decongestant spray through his nose.Nasal decongestant spray can offer temporary relief from sinusitis. 

Antibiotics

If a bacterial infection is suspected, your doctor may prescribe an oral antibiotic, such as amoxicillin, cefaclor or doxycycline. Antibiotics are not usually prescribed if the sinusitis is caused by a viral infection.

Corticosteroids

In addition to reducing your body's overall immune response, corticosteroid medications decrease mucus production and can also shrink nasal polyps. Some examples of corticosteroids, that can be sprayed directly into the nose, include triamcinolone acetonide, budesonide, fluticasone and mometasone.

If these sprays are not effective, your doctor may prescribe budesonide, which can be added to a salt water flush to reach further into the sinuses. Alternatively, an oral corticosteroid tablet, such as prednisolone, may be recommended. When swallowed, these medications enter the bloodstream, producing a stronger response throughout the whole body.

However, oral corticosteroids are not usually prescribed for more than two weeks, as long-term side effects can include high blood pressure (hypertension), eye problems, thinning of the skin and weight gain.

Surgery

If you have chronic sinusitis or previous treatments have not worked, you may be referred to an ENT specialist to discuss a possibility of surgery. Due to the risk of complications associated with any surgery, other treatment options are usually considered first. However, the benefits of surgery may outweigh the risks in some groups, particularly in people who have sinusitis due to a severe fungal allergy or structural issue, such as polyps, large adenoids, or a damaged or crooked nose (deviated septum).

Sometimes surgery may only provide short-term benefits without addressing the underlying cause of sinusitis. In these situations, symptoms may return, or need ongoing medications after surgery.

Adenoids

A mass of immune tissue in the back of the nose.

Allergy

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Nasal polyps

Fleshy outgrowths or lumps from the internal lining of the nose and sinus, often due to allergies, that can cause nasal obstruction and sinusitis.

Potential complications

The most common complication of short-term (acute) sinusitis is progression of the condition to long-term (chronic) sinusitis, which can last for weeks or months. Additional complications are rare, but can become serious if left untreated. They also tend to be more common in children.

Sinusitis can be particularly dangerous when the infection spreads from the nose and sinuses to one of the following areas:

  • Eye (orbital cellulitis);
  • Bones (osteomyelitis);
  • Blood (sepsis), or;
  • Brain (meningitis).

Sinusitis caused by a fungus can spread particularly fast, as this type of infection tends to occur in people with a weakened immune system. If you experience redness, swelling or drooping in your eyelids or cheeks, seek urgent medical attention.

Other possible complications include an abscess, middle ear infection, blood clots or asthma flare-ups.

Abscess

A swollen area of tissue containing a build-up of pus.

Prognosis

Although sinusitis can be uncomfortable and painful, most cases clear in 7-10 days without visiting a doctor or using prescription medications. Severe or long-term symptoms could be a sign of another issue, such as a bacterial infection, medical condition, allergy or structural abnormality in your nose or sinuses. The outcome in these situations can vary depending on the cause of symptoms.

Allergy

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.

Prevention

Sinusitis can be prevented by avoiding contact with people who have a cold or the flu. Good hygiene habits, such as washing your hands and covering your mouth when coughing or sneezing, can also help to prevent the spread of viruses. Staying away from organised activities is usually recommended until you are feeling well again.

Vaccinations against the flu virus and Streptococcus pneumonia (also known as pneumococcal) bacteria can also help to prevent sinusitis, particularly in children, the elderly and people with a weakened immune system.

Managing allergies effectively and avoiding any environmental triggers of sinusitis, such as pollution and cigarette smoke, may also help to prevent symptoms in some people.

Allergies

A harmful, hypersensitive immune reaction to usually innocuous environmental substances.