What Is Sinusitis?

Sinusitis is an inflammation of the inner lining of the sinuses in the face. This inner lining becomes swollen and red.

The sinuses are hollow spaces in some of the bones in the face. Air passes in and out of these spaces, and a fluid called mucus drains through openings in the sinuses and out of the nose. The sinuses reduce the weight of the skull and give our voices a nicer sound.

In sinusitis, the swelling of the lining of the sinuses blocks the openings in the sinuses through which mucus drains into the nose. When mucus cannot drain properly, the pressure of the blocked fluid inside the sinuses can be painful.

Sinusitis is quite common. It feels much like a head cold, with a stuffy or runny nose and a headache. For most people, sinusitis is a temporary condition that goes away with simple treatment. If the symptoms do not clear up easily, medication can help. In rare cases, surgery may bring permanent relief.

There are four main pairs of sinus openings, sometimes called sinus cavities, in the face:

  • Maxillary – in the cheekbones
  • Ethmoid – between the eye sockets
  • Frontal – in the forehead and above the eyebrows
  • Sphenoid – deep in the head at the back of the nose

Each of these pairs of sinus openings has a channel that leads to the nose. These channels are quite narrow and can be easily blocked when the lining of the channels becomes swollen. This lining is called the mucous membrane. This same mucous membrane forms the inner lining of the nose.

The mucous membrane in the nose and sinuses is our personal air filter. It warms, moistens, and cleans the air. The mucous membrane creates a clear, wet, slightly sticky mucus that gathers any dust, smoke, bacteria, or virus particles that may have been in the air.

Tiny hairs along the membrane called cilia act as miniature oars, moving the mucus along, much like a conveyor belt, through the sinuses and out the nose. When the mucus containing the unwanted particles reaches the nose and throat, the body prompts us to swallow, spit, sneeze, or cough them out of the body. But when the sinus openings become blocked, cilia can no longer move the mucus through.

The mucous membrane is also one of the body’s front-line defense systems. It releases chemicals that help to destroy bacteria and viruses before they can attack.

How Is Sinusitis Different From Rhinitis?

Rhinitis results in a basic runny nose, sometimes accompanied by facial pain and a headache. It is caused by a swelling of the mucous membrane of the nose only, rather than the mucous membrane of the sinuses.

Rhinitis is much more common than sinusitis and is more frequently caused by allergies than by a bacteria or virus. Many people, especially children, experience rhinitis during the winter months as a reaction to the cold air.

Most cases of sinusitis are actually a combination of rhinitis and sinusitis, meaning that the mucous membranes of both the nose and sinuses are swollen. This condition is sometimes called rhinosinusitis.

How Common Is Sinusitis?

Almost everyone experiences rhinitis at some point in their lives, and the majority of people will also experience sinusitis.

Sometimes, a simple head cold will turn into sinusitis if the body has difficulty fighting off the bacteria or virus that caused the cold. This is the case when the body aches and fatigue from a cold go away, but the runny nose and postnasal drip symptoms continue and worsen.

Facts about sinusitis

  • Each year, sinusitis affects about 37 million Americans.
  • It is the most frequently reported chronic condition in the United States and the fifth most common reason for taking an antibiotic.
  • It accounts for more than 13 million doctor visits per year in the United States alone.
  • Medical costs for the treatment of sinusitis in the United States are estimated at $2 billion per year. This does not include the few cases that require more costly x-rays and surgery.
  • Modern-day pollution has increased the number of people suffering from allergies. As a result, sinusitis is also on the rise.


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