Sinus Infection Overview

Sinus infection, or sinusitis, is an inflammation of the sinuses and nasal passages. A sinus infection can cause a headache or pressure in the eyes, nose, cheek area, or on one side of the head.

A person with a sinus infection may also have a cough, a fever, bad breath, and nasal congestion with thick nasal secretions. Sinusitis is categorized as acute (sudden onset) or chronic (long term, the most common type).

Anatomy of the sinuses (also called paranasal sinuses): The human skull contains 4 major pairs of hollow air-filled sacks called sinuses. These connect the space between the nostrils and the nasal passage. Sinuses help insulate the skull, reduce its weight, and allow the voice to resonate within it.

  1. Frontal sinuses (in the forehead)
  2. Maxillary sinuses (behind the cheek bones)
  3. Ethmoid sinuses (between the eyes)
  4. Sphenoid sinuses (behind the eyes)

Acute sinusitis:

  • Ethmoid sinusitis (behind the eyes)
    • Nasal congestion with discharge or postnasal drip (mucus drips down the throat behind the nose)
    • Pain or pressure around the inner corner of the eye or down one side of the nose
    • Headache in the temple or surrounding the eye
    • Pain or pressure symptoms worse when coughing, straining, or lying on the back and better when the head is upright
  • Maxillary sinusitis (behind the cheek bones)
    • Pain across the cheekbone, under or around the eye, or around the upper teeth
    • Pain or pressure on one side or both
    • Tender, red, or swollen cheekbone
    • Pain and pressure symptoms worse with the head upright and better by reclining
    • Nasal discharge or postnasal drip
    • Fever common
  • Frontal sinusitis (behind forehead, one or both sides)
    • Severe headaches in the forehead
    • Fever common
    • Pain worse when reclining and better with the head upright
    • Nasal discharge or postnasal drip
  • Sphenoid sinusitis (behind the eyes)
    • Deep headache with pain behind and on top of the head, across the forehead, and behind the eye
    • Fever common
    • Pain worse when lying on the back or bending forward
    • Double vision or vision disturbances if pressure extends into the brain
    • Nasal discharge or postnasal drip

Chronic sinusitis:

  • Ethmoid sinusitis
    • Chronic nasal discharge, obstruction, and low-grade discomfort across the bridge of the nose
    • Pain worse in the late morning or when wearing glasses
    • Chronic sore throat and bad breath
    • Usually recurs in other sinuses
  • Maxillary sinusitis
    • Discomfort or pressure below the eye
    • Chronic toothache
    • Pain possibly worse with colds, flu, or allergies
    • Increased discomfort throughout the day with increased cough at night
  • Frontal sinusitis
    • Persistent, low-grade headache in the forehead
    • History of trauma or damage to the sinus area
  • Sphenoid sinusitis
    • Low-grade general headache common. A doctor often can treat simple sinusitis. If left undiagnosed and untreated, though, complications of sinusitis can occur that may lead to severe medical problems and possibly death. The following complications are medical emergencies and require immediate treatment in a hospital’s emergency department.
    • Headache, fever, and soft tissue swelling over the frontal sinus may indicate an infection of the frontal bone, called Pott puffy tumor or osteomyelitis. Usually, this complication is limited to children.
    • Infection of the eye socket may result from ethmoid sinusitis. The eyelid may swell and become droopy. Fever and severe illness are usually present. A person with this infection may lose the ability to move the eye, and permanently blindness may result.
    • Ethmoid or frontal sinusitis may also cause the formation of a blood clot in the sinus area around the front and top of the face. Symptoms may be similar to those of eye socket infection with the addition of a fixed and dilated pupil. This condition usually affects both sides of the face.
    • If a person experiences mild personality changes, headache, altered consciousness, visual problems, or seizures, infection may have spread to the brain. Coma and even death may follow.


Some people experience chronic sinusitis despite adequate therapy with antibiotics and drugs for relief of symptoms. Those that have a CT scan indicative of sinus infection as well as those with any complications of sinusitis may benefit from sinus surgery.

  • The surgery is performed endoscopically using the same fiberoptic nasopharyngoscope used to make the diagnosis.
  • The goal is to remove obstructive mucosal disease, open the OMC or nasal passageway, and allow drainage of the sinuses.
  • During the surgery, nasal polyps can also be removed, and a crooked nasal septum can be straightened, leading to improved airflow.
  • Long-term nasal steroids and periodic antibiotics may still be necessary.
  • A continuing sinus infection may need further investigation. A culture obtained during a routine office visit or during endoscopic surgery may reveal anaerobes, which require treatment of broad-spectrum antibiotic drugs, or fungi, which require treatment of antifungal medications.

Next Steps Follow-up

People whose symptoms of a sinus infection do not go away despite the use of antibiotics should follow up with their doctors or ear, nose, and throat specialists in 5-7 days.


Sinusitis or sinus infections usually clear up if treated early and appropriately. Aside from those who develop complications, the outlook for acute bacterial sinusitis is good. People who have allergic or structural causes for their sinusitis may have recurrent attacks of acute sinusitis or may develop chronic sinusitis.

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Bang-0, Bangplad

Bangkok 10700, Thailand

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