What Causes Sinusitis?

There are two different types of sinusitis, and each has different causes:

  • Acute sinusitis
  • Chronic sinusitis

Acute Sinusitis

Acute sinusitis means that the symptoms of the condition are temporary, usually lasting no more than 30 days. However, the symptoms of acute sinusitis are more severe and painful than the symptoms of chronic sinusitis.

The most common causes of acute sinusitis are:

  • Virus. Viral infections can paralyze or even destroy the cilia so that they are unable to move mucus out of the nose.
  • Bacteria. If the sinus openings become blocked and the infected mucus cannot move out of the body or drain down the throat, it creates is an ideal environment for bacteria to grow. The bacteria in turn creates an acid environment in the sinuses, which further paralyzes the cilia. This causes the mucous membrane to swell more. The sinus openings become even more blocked.
  • Fungus. Fungus is a plant or mold, often microscopic, that can be ingested with food or inhaled in the air. Once in the body, it can affect the immune system and aggravate the sinuses.
  • Nose blowing. Bacterial infections can be caused by pressure from blowing the nose too much.
  • Scuba diving. Scuba diving while suffering from a cold can create too much pressure in the sinuses and leave room for bacteria to grow.
  • Foreign objects. Young children sometimes try to put objects in their nostrils, and this can introduce bacteria into the sinuses.
  • Medications. The side effect of certain medications may affect the functioning of the mucous membrane.
  • Diseased teeth. On rare occasions, the maxillary sinus in the cheekbone becomes infected by the root of a diseased upper tooth.

Need To Know:

Acute sinusitis is typically the result of a cold that lingers on too long and becomes an infection. It is important to treat acute sinusitis early to prevent the infection from spreading.

Chronic Sinusitis

Chronic sinusitis means that the symptoms of sinusitis occur frequently or for long periods of time. The symptoms are usually more annoying than painful. However, those with chronic sinusitis are more likely to have recurring attacks of acute sinusitis, which can be quite painful.

Chronic sinusitis is often a combination of swelling caused by allergies or fungus, or by bacteria or a virus.

Anything that interferes with the normal functioning of the mucous membrane can bring on symptoms. When mucus cannot drain properly, bacteria has a perfect environment in which to grow.

Chronic sinusitis is most often caused by:

  • Allergies. Allergies can be caused by almost anything. However, the most common allergens are airborne particles, foods, animals, feathers, and fabrics. If the culprit is a food, fabric, or animal, simply avoiding the allergen will stop symptoms. If the allergen is a chemical or substance in the air, such as dust or ragweed, treatment such as regular allergy shots for a period of time can provide relief.

    For more information about food allergies, go to Food Allergies & Interolance.

  • Asthma. Adults and children suffering from asthma are more prone to sinusitis.

    For more information about asthma, go to Asthma In Children or Asthma.

  • Temperature and humidity. When temperature and humidity are extreme, or when these air conditions change quickly, the sinuses can become irritated.
  • Narrow sinuses. Some people simply have narrow sinus openings or a deviated septum, so that when there is swelling, it is even more difficult for air to pass through.
  • Defective mucous membrane. Some people have poorly functioning mucous membranes, sometimes permanently damaged by a past infection.
  • Dehydration. Not drinking enough liquids will cause dehydration. Without enough fluid in the body, the mucus will thicken, making it difficult for the cilia to move it through the sinuses.
  • Poor air quality. Pollution, fumes, dust, smoke or crowded living conditions – anything that reduces the quality of the air – can affect the function of the sinuses and mucous membrane.
  • Weak immune system. When the immune system is not strong, the mucous membrane and cilia cannot do their job to resist infection. Immune deficiency can be caused by poor diet, medication side effects, or diseases such as HIV and AIDS.
  • Hormones. In a few cases, hormonal imbalances can lead to sinusitis.
  • Stress. Research shows that the mucous membrane and sinuses can react to stress. One such condition is known as vasomotor rhinitis, in which stress, rather than an infection or allergy, causes excessive swelling and mucus production.

    For more information about stress, go to Stress And How To Manage It.

  • Polyps. In rare cases, polyps are the cause of sinusitis. Polyps are benign (noncancerous) water-filled swellings about the size of grapes that develop in the sinuses. They most frequently occur in people who have asthma. Polyps generally need to be surgically removed.
  • Tumors. One of the most rare causes of sinusitis are tumors, which need to be surgically removed from the sinuses.

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