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Bacterial Sinusitis

Written by Ada’s Medical Knowledge Team

Updated on

What is bacterial sinusitis?

Bacterial sinusitis is a bacterial infection of the paranasal sinuses, the hollow spaces in the bones of the face around the nose. Sinusitis is a very common problem, affecting approximately one in every eight American adults annually. Almost 30 million people seek medical help for sinusitis in the USA every year. 1

Bacterial sinusitis involves inflammation of the mucous membrane lining of the sinuses, and is caused by a bacterial infection. There are four pairs of paranasal sinuses which are located below, above, between and behind the eye sockets – the maxillary sinuses, frontal sinuses, ethmoid sinuses and sphenoidal sinuses. The maxillary sinuses are the largest of these, and are most often affected by sinusitis. However, sinusitis can affect any or all of the paranasal sinuses. Because sinusitis often occurs along with rhinitis, inflammation of the mucous membrane in the nose, it is sometimes known as rhinosinusitis. 2

Bacterial sinusitis often follows a viral infection, such as a cold or the flu. Viral infections can cause the mucosal lining of the sinuses to swell. 3 In healthy sinuses, mucus drains into the nasal cavity via small holes, known as ostia. Swelling of the mucus membranes in the nose or sinus cavities can block these holes, preventing mucus from draining out of the sinuses. Bacteria colonize the undrained mucus, which can lead to bacterial sinusitis. 2

Bacterial sinusitis may be treated with anti-inflammatory medications, and antibiotics as needed. Most cases of bacterial sinusitis resolve within two weeks, and have no further symptoms.

Signs and symptoms of bacterial sinusitis

Viral sinusitis vs bacterial sinusitis

Viral sinusitis is the most common type of sinusitis. It is usually caused by the same viruses that cause the common cold and typically lasts for between 7 and 10 days. 4 If the condition lasts longer than 10 days, or there is a worsening of symptoms after 5 to 7 days, the sinusitis is more likely caused by bacteria than a virus. 3

Acute, subacute and chronic bacterial sinusitis

Bacterial sinusitis can be grouped into the following subtypes based on the duration of symptoms: 2 4 5

  1. Acute, which lasts for less than four weeks
  2. Subacute, lasting for between four and 12 weeks
  3. Chronic, lasting for more than 12 weeks
  4. Recurrent acute, occurring four or more times a year, for more than 7 days, with symptoms resolving completely in between bouts

Symptoms of bacterial sinusitis

Symptoms of bacterial sinusitis include: 1 2 4 6

  • Pressure or pain around the nose, in the forehead, in the cheeks or around the eyes. The pain often gets worse if the affected person bends forward.
  • Discolored, thick nasal discharge
  • Decreased sense of smell and ability to taste
  • Stuffy nose
  • Bad breath

In some cases, affected people may also experience:

  • Coughing or sore throat
  • Post-nasal drip (mucus dripping down the back of the throat)
  • Ear pain or a feeling of fullness in the ears
  • Fever
  • Fatigue
  • Facial pain
  • Painful teeth
  • Painful chewing 2

Good to know: Bacterial sinusitis can follow a cold or the flu, and often the symptoms occur just when it seems as if the initial infection is clearing up. In this situation it is common to start to feel better, and then to feel worse as the subsequent bacterial sinusitis develops.

Symptoms of bacterial sinusitis in children

In children, the symptoms of sinusitis may differ from those in adults. Children may experience: 4 6

  • Irritability
  • Ear discomfort
  • Lethargy
  • Snoring
  • Mouth breathing
  • Difficulty feeding
  • Nasal speech 4

Good to know: Bacterial sinusitis can affect children of any age, even though the paranasal sinuses are not visible on X-ray before the age of about nine.

Causes of bacterial sinusitis

The condition is caused by bacteria that live in the nose, throat and, sometimes, the mouth. Types of bacteria which commonly cause bacterial sinusitis include: 1 2 5

  • Streptococcus pneumoniae
  • Hemophilus influenzae
  • Staphylococcus aureus
  • Moraxella catarrhalis

As detailed above, bacterial sinusitis often follows a cold or flu infection. Other conditions that can increase a person’s risk of bacterial sinusitis include: 1 4 6

  • Allergies
  • Asthma
  • Smoking
  • Nasal obstruction, for example due to nasal polyps or a deviated nasal septum (the wall between the nasal cavities)
  • Congenital disease such as cystic fibrosis
  • Conditions which cause a weakened immune system, such as HIV infection, leukemia or immunosuppressive therapy following an organ transplant
  • Diabetes
  • Hormonal changes, for example those that occur during pregnancy
  • Irritating inhalants, such as cocaine
  • Fungal infections
  • Scar tissue in sinus areas, for example from nasogastric tubes or mechanical ventilation
  • Facial fractures
  • Tooth or mouth infections such as a dental abscess (infection may spread due to the close proximity of the maxillary sinuses to the upper jaw)

In general, women are slightly more likely than men to get bacterial sinusitis.

If you’ve had a cold or any of the disorders listed above, and you’re concerned that you may have bacterial sinusitis, check out the Ada app for a free symptom assessment.


The diagnosis is based on the symptoms and physical examination. In severe cases or cases that do not respond to treatment, a nasal endoscopy may be done to aid diagnosis and treatment.

Endoscopic diagnosis

An endoscope is a small, flexible tool equipped with a camera, which allows the doctor a detailed view of the inside of the nose and sinuses. The endoscopic examination is usually done in the doctor’s office. A nasal decongestant will be administered, and the nose will be numbed by an anesthetic spray. If the endoscopic exam is not helpful or if the doctor wants to carry out further examination, a ct scan may be ordered. A CT scan can be helpful in assessing the sinuses and confirming the diagnosis in complicated cases.


Most cases of bacterial sinusitis will get better without antibiotics, usually within 14 days. 4 Because of this, and because bacterial sinusitis is often caused by bacteria that are to some degree resistant to antibiotics, most doctors prefer that affected people initially try to manage the condition using home remedies and over-the-counter medications. Antibiotics are usually only prescribed for people who have severe or ongoing symptoms, or whose infection may be complicated by various other medical factors. Viral sinusitis does not respond to antibiotic treatment.

Although most cases of bacterial sinusitis clear up without the help of a doctor, affected people should seek medical assistance if: 2

  • They have a fever of 101.4 F / 38 C or higher
  • They have a bad headache that is not relieved by basic painkillers such as paracetamol
  • They have any signs of eye involvement (visual changes, pain moving the eyes, or any swelling or redness around the eye)
  • They have had symptoms for more than 10 days
  • Their symptoms are worsening
  • They have had antibiotic treatment, but the symptoms persist

Home remedies for bacterial sinusitis

In many cases, home remedies may be sufficient. Some people find breathing humid air or steam, such as in a warm shower, helps to relieve symptoms. Also, holding a warm pad over the painful area helps to relieve discomfort. Nasal irrigation with saline solution is helpful in reducing congestion in the nose. It is also very important to stay well-hydrated, so affected people should be sure to drink enough fluids.

Over-the-counter remedies

Painkillers such as ibuprofen or paracetamol can help reduce the nose and face pain. Decongestant and anti-inflammatory sprays or tablets are also often helpful in relieving symptoms. Decongestants commonly used are pseudoephedrine and phenylephrine. Fluticasone is a corticosteroid used to suppress the inflammation. 6 5

Good to know: If over-the-counter decongestant nasal sprays or drops are being used, they should only be used for up to 3 days in a row as they may cause rebound congestion if used for longer. These products do not shorten the duration of bacterial sinusitis but may relieve symptoms. Antihistamines are not recommended as a treatment for bacterial sinusitis as they increase nasal dryness and discomfort by making mucus thicker and harder to drain.

Antibiotic treatment for bacterial sinusitis

Antibiotic treatment is usually only needed if the infection does not improve within 7-10 days, the person has another medical condition which may affect recovery, or if: 5 6

  • Severe pain is present
  • Swelling at the front of the head, cheeks or around the eyes occurs
  • Nasal discharge contains blood
  • High fever is present

These are indications that the bacterial infection is severe. Antibiotic treatment is usually prescribed for about 10 days, but shorter courses may be as effective, depending on the bacteria involved. The choice of which antibiotic to use will be based on which bacteria the treating physician thinks are likely to be involved in the infection. 1

Surgical treatment for bacterial sinusitis

Surgery is not usually needed for acute bacterial sinusitis. It is only necessary in some cases of chronic sinusitis that do not respond to other forms of treatment. Endoscopic treatment, where a small camera-equipped probe is used to guide and perform the procedure, is one option. In this surgery, the endoscope is used to widen the natural drainage pathways in the sinuses and nose, which improves mucus drainage and cuts down on congestion and the chance of infection. 3

Rarely, acute bacterial sinusitis may cause an abscess to form near the eye or the brain. In these cases, surgical treatment will be needed to drain the abscess. 1

Good to know: Complications from bacterial sinusitis are rare, affecting only about one in every ten thousand people with the disorder. However, they are more common among children than adults, so caregivers of children with suspected bacterial sinusitis should exercise caution and be alert for worsening symptoms, swelling or redness of any area of the child’s face. 6


Taking care to prevent the spread of colds or the flu in the home and community can help prevent some cases of bacterial sinusitis. Seeing a dentist regularly may help to prevent tooth infections, a possible cause of bacterial sinusitis.


Q: Can bacterial sinusitis cause a sore throat?
A: Bacterial sinusitis may be accompanied by postnasal drip, an uncomfortable condition where excess mucus can irritate the throat. Additionally, if bacterial sinusitis was preceded by a viral upper respiratory illness, a sore throat may have been a feature of this.

If you feel unwell with a cough, a headache and a scratchy throat, check out the Ada app for a free symptom assessment.

Q: Where are the paranasal sinuses?
A: There are four pairs of paranasal sinuses: the maxillary, frontal, ethmoid and sphenoidal. The maxillary sinuses are located below the eyes, and the frontal sinuses are above the eyes. Both of these are near the front of the head, near the inner corners of the eyes. The ethmoid sinuses are located in the ethmoid bone, which separates the brain from the nasal cavity; the sinuses themselves are between the eyes. The sphenoid sinuses are behind the eyes. The maxillary sinuses are most commonly affected by sinusitis.