Sinusitis: Symptoms, causes, and treatment

Sinusitis is a common inflammation of the paranasal sinuses, the cavities that produce the mucus necessary for the nasal passages to work effectively.

It can be acute or chronic, and it can be caused by viruses, bacteria, fungi, allergies, or even an autoimmune reaction.

Although uncomfortable and painful, sinusitis often goes away without medical intervention. However, if symptoms last more than 7 to 10 days, or if there is a fever or a bad headache, you should see your doctor.

In 2015, the Centers for Disease Control and Prevention (CDC) noted that 12.1 percent of adults surveyed in the United States (U.S.) had been diagnosed with sinusitis in the previous 12 months.

Fast facts on sinusitis

Here are some key points about sinusitis. More detail is in the main article.

People have four pairs of sinuses, hollow spaces behind the bones of the face.

Allergies, bacteria or a virus can cause inflammation of the sinuses, or sinusitis.

It usually goes away without treatment, but sometimes medical attention is needed.

Chronic sinusitis lasts more than 12 weeks.

What is sinusitis?

Pain in the nasal passages can be a sign of sinusitis.
Pain in the nasal passages can be a sign of sinusitis.

A sinus is a hollow space in the body. There are many types of sinus, but sinusitis affects the paranasal sinuses, the spaces behind the face that lead to the nasal cavity.

The paranasal sinuses have the same mucous membrane lining as the nose.They produce a slimy secretion called mucus. This keeps the nasal passages moist and traps dirt particles and germs.

Sinusitis occurs when mucus builds up and the sinuses become inflamed.

Doctors often refer to sinusitis as rhinosinusitus, because inflammation of the sinuses nearly always occurs with inflammation of the nose known as rhinitis.


Symptoms vary, depending on the length and severity of the infection.

If the patient has two or more of the following symptoms and thick, green or yellow nasal discharge, they may be diagnosed with acute sinusitis.

facial pain and pressure

blocked nose

nasal discharge

reduced sense of smell



In more advanced cases, the following symptoms may also be present:


halitosis, or foul-smelling breath




If these symptoms continue for 12 weeks or longer, the doctor may diagnose chronic sinusitis.

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Sinusitis can stem from various factors, but it always results from fluid becoming trapped in the sinuses. This fuels the growth of germs.

Viruses: In adults, 90 percent cases of sinusitis result from a virus

Bacteria: In adults, 1 case in 10 is caused by bacteria

Pollutants: Chemicals or irritants in the air can trigger a buildup of mucus

Fungi: The sinuses either react to fungi in the air, as in allergic fungal sinusitis (AFS), or they are invaded by fungi, as in chronic indolent sinusitis. This is rare in the U.S.

Risk factors

The following may increase a person’s risk of developing sinusitis:

previous respiratory tract infections, such as the common cold

nasal polyps, or small growths in the nasal passage that can lead to inflammation

weakened immunity, due, for example, to a health condition or some kinds of treatment

an allergic reaction to substances such as dust, pollen, and animal hair

structural problems in the nose, for example, a deviated septum

The septum is the bone and cartilage that divides the nose into two nostrils. When this is bent to one side, either through injury or growth, it can lead to repeated infections and inflammation.


Sinusitis always involves nasal swelling and a buildup of mucus, but there are different types, and they can last for different lengths of time.

The different types are:

Acute sinusitis: This lasts up to 4 weeks and is the most common type.

Subacute sinusitis: Symptoms last longer than the normal acute period, for between 4 and 12 weeks.

Chronic sinusitis: Symptoms persist, or continually return, after 12 weeks. It may need more invasive treatment, and possibly surgery.

Recovery time and treatment depend on the type of sinusitits.


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