Sinusitis is inflammation (swelling) of the lining of the sinuses, caused by a viral or bacterial infection.

The sinuses are small, air-filled cavities behind your cheekbones and forehead (see below). 

Sinusitis typically causes a high temperature, pain and tenderness in the face, and a blocked or runny nose (see Sinusitis symptoms).

It is a common condition and can affect people of any age.

The sinuses

You have four pairs of sinuses in your head:

• two sinuses behind your forehead
• two at either side of the bridge of your nose
• two behind your eyes
• two behind your cheekbones

Your sinuses open up into the cavity of your nose and help control the temperature and water content of the air reaching your lungs. 

Usually, the mucus naturally produced by your sinuses drains into your nose through small channels. These channels can become blocked when the sinuses are infected and inflamed.

It is the sinuses behind the cheekbones (the largest ones) that are most commonly affected.

Acute and chronic sinusitis

Sinusitis is classed as either:

• acute, when it develops quickly (over a few days) following a cold or flu and clears up within 12 weeks, or
• chronic, when symptoms last for more than 12 weeks.

Chronic sinusitis is less common and can sometimes last for many months.

Outlook

Sinusitis often clears up by itself, and about two thirds of those who get the condition do not need to see their GP.

On average, sinusitis takes about two-and-a-half weeks to clear.

Over-the-counter painkillers and decongestants can be used to relieve facial pain and a blocked nose. Antibiotics are unlikely to help unless the sinusitis becomes persistent.

The most common symptoms of sinusitis include:

• A blocked or runny nose. If your nose produces green or yellow mucus, you probably have a bacterial infection.
• Pain and tenderness in the face (near the infected sinuses). You may experience a throbbing pain that is worse when you move your head, and toothache or pain in your jaw when you eat.
• A high temperature.

Other possible symptoms include:

• tiredness
• a sinus headache
• a cough
• bad breath (halitosis)
• pressure in your ears
• loss of taste and smell
• a feeling of being generally unwell

Children

Children with sinusitis may be irritable, breathe through their mouth and have difficulty feeding.

Their speech may sound nasal (like they have a stuffy cold) because their sinuses are blocked.

If you notice these symptoms in your child, take them to see your GP.

There are a number of ways your sinuses can become inflamed and blocked, but the most common cause is a viral infection.

Infections

The most common cause of sinusitis is the common cold or influenza (flu). The cold or flu virus spreads to the sinuses from the upper airways.

Sometimes, a secondary bacterial infection can develop, leading to swelling inside the sinuses.

An infected tooth may also cause the sinuses to become infected. 

Other causes

There are a number of other factors that can make the sinuses more vulnerable to infection. These include:

• Substances that may irritate the sinuses, such as air pollution, smoke, chemicals (such as pesticides), disinfectants and household detergents.
• Allergies, such as allergic rhinitis, asthma and hayfever.
• Anything that causes narrowing of the nose passages, such as facial injuries or nasal polyps (growths) inside the nose. Mucus can build up behind the narrowed areas, leading to sinus infection.
• Cystic fibrosis, a genetic condition that causes thick, sticky mucus to build up within the body, making you prone to infections.   

Glossary

Lesions

A lesion is an abnormal change in an organ or body tissue because of injury or disease.

Genetic

Genetic is a term that refers to genes- the characteristics inherited from a family member.

Fever

A high temperature, also known as a fever, is when someone's body temperature goes above the normal 37°C (98.6°F).

Inflammation

Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Chemotherapy

Chemotherapy is a treatment of an illness or disease with a chemical substance, e.g. in the treatment of cancer.

Your GP can usually diagnose sinusitis from your symptoms.

Sinusitis is nearly always caused by a viral infection, such as the common cold or flu, and is diagnosed based on the presence of:

• nasal blockage or runny nose with facial pain, and/or
• a reduction or loss of sense of smell

Loss of smell is more common and facial pain less common in chronic (persistent) sinusitis.

Referral to a specialist

If your sinusitis is severe or keeps coming back, your GP may refer you to an ear, nose and throat (ENT) specialist who will carry out tests to determine the underlying cause.

You may have an X-ray or CT scan to find out the cause of your sinusitis (a series of X-rays are taken for a CT scan, to produce a detailed picture of your sinuses).

Glossary

Bacteria

Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some others are good for you.

X-ray

An X-ray is a painless way of producing pictures of inside the body using radiation.

About two thirds of people who get sinusitis do not need to see their GP. Most cases are caused by a viral infection, which often clears up by itself.

Sinusitis takes about two-and-a-half weeks to clear, so it lasts longer than the common cold.

If you have mild sinusitis you can take over-the-counter painkillers and decongestants to relieve your symptoms (see box, right).

Seeking treatment from your GP

See your GP if your symptoms do not improve after seven days, if they are getting worse, or if the sinusitis keeps coming back.

In these cases, treatment options are:

• antibiotics
• steroid sprays or drops
• surgery (if other treatments have failed).

However, these treatments are only used for severe cases of sinusitis.

Your GP may refer you to an ear, nose and throat (ENT) specialist, who will carry out some tests to determine the underlying cause of your chronic (persistent) sinusitis. Chronic sinusitis may last for several months.

Antibiotics

If your symptoms are severe and your sinusitis has not cleared within seven days, your GP may prescribe you antibiotics. About one third of people with sinusitis will develop a bacterial infection that requires antibiotics.

Steroid sprays or drops

Steroid sprays, drops or implants are usually prescribed if you are diagnosed with chronic sinusitis, as they can help to reduce your swollen sinuses.

Surgery

If your symptoms do not improve after a course of antibiotics, and you are still experiencing difficulties with your affected sinuses, functional endoscopic sinus surgery (FESS) may be recommended. This is the most common operation for sinusitis and can be successful in relieving the symptoms. 

FESS is usually done under general anaesthetic (you are put to sleep), but it can also be done under local anaesthetic (where your nose is numbed).

The surgeon will insert an endoscope into your nose. This is a thin tube with a lens that magnifies the inside of your nose. They will then be able to see the opening of your sinus drainage channels.

The surgeon will either:

• remove any tissues, such as nasal polyps (growths), which are blocking the affected sinus
• inflate a tiny balloon inside your nose, to open up the drainage passages from your sinuses (this is called a balloon catheter dilation)

The operation will improve your sinus drainage and will help the sinus to function properly.

The surgeon may also insert a self-dissolving implant into your sinuses, which expands to prop the sinuses open and deliver the steroid drug mometasone directly to the sinus lining.

For more information, read ENT UK's leaflet on functional endoscopic sinus surgery and the 2008 guidelines from the National Institute for Health and Clinical Excellence (NICE) on balloon catheter dilation for chronic sinusitis.

Glossary

Immune system

The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

Antibiotics

Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi. For example amoxicillin, streptomycin and erythromycin.

Decongestants

Decongestant medicine relieves congestion by reducing the swelling of the lining the nose and sinuses and drying up the mucous.

Complications in children

Complications of sinusitis are more common in children than in adults. If your child has had sinusitis and has swelling around the cheekbone or eyelid, it may be a bacterial infection of the skin and soft tissue or an infection of the tissue surrounding the eye. Read about cellulitis for more information.

If you notice these symptoms, take your child to see your GP, who may refer them to an ear, nose and throat (ENT) specialist. Alternatively, you can call NHS Direct on 0845 46 47 for information and advice.

Infection of the bone

When the condition is severe, antibiotics are often able to control the spread of infection to the nearby bone. However, in very rare cases (about one in 10,000), infection can spread to the area surrounding the eye, the bones, the blood or the brain.

Glossary

Tissue

Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.  

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

Blood

Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Antibiotics

Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi. For example amoxicillin, streptomycin and erythromycin.

Acute

Acute means occuring suddenly or over a short period of time.

Swelling

Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Chronic

Chronic usually means a condition that continues for a long time or keeps coming back.