Sinus infection, also called sinusitis, is an inflammation of the tissues lining the paranasal sinuses. Acute sinusitis lasts less than 4 weeks, while chronic sinusitis persists for more than 12 weeks. Viral infections account for most cases, whereas bacterial infections represent a smaller percentage.
At American Urgent Care and Walk-In Clinics, patients receive prompt medical evaluation for common illnesses and injuries, including respiratory infections and sinus conditions.
What Is a Sinus Infection?
A sinus infection is inflammation and swelling inside the air-filled cavities around the nose.
The paranasal sinuses include four pairs of cavities:
- Frontal sinuses above the eyebrows
- Maxillary sinuses behind the cheeks
- Ethmoid sinuses between the eyes
- Sphenoid sinuses behind the nasal cavity
Healthy sinuses contain air and a thin layer of mucus. Infection or inflammation blocks normal drainage and increases mucus accumulation.
What Causes a Sinus Infection?
Viruses cause approximately 90% to 98% of acute sinus infections.
Common causes include:
- Viral respiratory infections, examples include rhinovirus and influenza virus.
- Bacterial infections, examples include Streptococcus pneumoniae and Haemophilus influenzae.
- Allergic rhinitis, examples include pollen allergy and dust mite allergy.
- Nasal polyps, examples include inflammatory growths inside the nasal cavity.
- Deviated nasal septum.
- Fungal infections, examples include Aspergillus species.
According to the Centers for Disease Control and Prevention, viral upper respiratory infections represent the most common source of acute sinusitis.
Common Symptoms of a Sinus Infection
Facial pressure, nasal congestion, and thick nasal discharge represent the most frequent symptoms.
Symptoms include:
- Nasal blockage
- Facial pain
- Facial pressure
- Thick yellow or green mucus
- Postnasal drip
- Reduced sense of smell
- Headache
- Ear pressure
- Bad breath
- Cough
Additional symptoms may include:
- Fever above 38°C (100.4°F)
- Tooth pain affecting upper teeth
- Fatigue
- Sore throat
Acute Sinus Infection Symptoms
Acute sinusitis develops rapidly and lasts less than 4 weeks.
Acute symptoms often follow a cold or upper respiratory infection. Symptom severity increases during the first 7 to 10 days.
Chronic Sinus Infection Symptoms
Chronic sinusitis continues for at least 12 weeks.
Persistent inflammation produces:
- Long-term nasal congestion
- Continuous mucus drainage
- Reduced smell sensation
- Recurrent headaches
- Ongoing facial pressure
Types of Sinus Infection
Sinusitis is classified according to duration and recurrence.
Acute Sinusitis
Acute sinusitis lasts fewer than 4 weeks.
Subacute Sinusitis
Subacute sinusitis lasts between 4 and 12 weeks.
Chronic Sinusitis
Chronic sinusitis persists longer than 12 weeks.
Recurrent Sinusitis
Recurrent sinusitis involves four or more episodes within one year.
How Doctors Diagnose a Sinus Infection
Diagnosis depends on symptom duration, physical examination, and medical history.
Healthcare professionals evaluate:
- Nasal congestion
- Facial tenderness
- Presence of mucus
- Fever
- Previous respiratory infections
Additional diagnostic methods include:
Nasal Endoscopy
Nasal endoscopy provides direct visualization of the nasal passages and sinuses.
A flexible tube equipped with a camera identifies structural abnormalities, inflammation, and polyps.
Computed Tomography Scan
CT imaging reveals detailed sinus anatomy and blockage patterns.
Computed tomography helps evaluate chronic and recurrent sinusitis.
Allergy Testing
Allergy testing identifies environmental triggers.
Examples include grass pollen, mold spores, and pet dander.
Treatment Options for Sinus Infection
Treatment focuses on reducing inflammation and restoring sinus drainage.
Home Management Measures
Common supportive measures include:
- Saline nasal irrigation
- Adequate hydration
- Humidified air exposure
- Warm facial compresses
Medications
Different medications target specific symptoms and underlying causes.
Examples include:
- Nasal corticosteroid sprays
- Antihistamines
- Decongestants
- Pain relievers
Antibiotics are prescribed for confirmed or strongly suspected bacterial infections.
Surgical Treatment
Functional endoscopic sinus surgery improves drainage in severe chronic cases.
Surgery addresses:
- Nasal polyps
- Structural abnormalities
- Persistent obstruction
Risk Factors for Sinus Infection
Certain medical and environmental factors increase susceptibility.
Risk factors include:
- Allergic rhinitis
- Asthma
- Smoking exposure
- Air pollution
- Immune system disorders
- Nasal polyps
- Deviated septum
People with asthma experience higher rates of chronic sinus inflammation compared with the general population.
Possible Complications
Complications are uncommon but involve nearby structures around the eyes and brain.
Potential complications include:
- Orbital cellulitis
- Bone infection
- Meningitis
- Brain abscess
- Vision impairment
These complications occur infrequently but require immediate medical attention.
How to Prevent Sinus Infection
Preventive measures reduce exposure to infectious agents and irritants.
Preventive strategies include:
- Washing hands regularly.
- Receiving annual influenza vaccination.
- Avoiding tobacco smoke.
- Controlling allergic rhinitis.
- Using humidifiers appropriately.
- Maintaining adequate hydration.
Statistics About Sinus Infection
Approximately 31 million adults in the United States experience sinusitis each year.
Chronic sinusitis affects nearly 12% of adults and contributes to millions of outpatient visits annually. Respiratory viruses remain responsible for most acute cases.
When Medical Evaluation Is Important
Persistent symptoms lasting longer than 10 days or severe symptoms require clinical assessment.
Warning signs include:
- Fever above 39°C (102.2°F)
- Facial swelling
- Vision changes
- Severe headache
- Neck stiffness
- Recurrent episodes
Early evaluation improves identification of bacterial infection and associated complications.
Conclusion
Sinus infection is an inflammatory condition affecting the paranasal sinuses and producing nasal congestion, facial pressure, and mucus accumulation. Viral infections account for most acute cases, while chronic sinusitis involves prolonged inflammation lasting at least 12 weeks. Diagnosis relies on symptom patterns, physical examination, and imaging studies in selected cases. Treatment focuses on improving drainage, reducing inflammation, and addressing underlying causes.
Frequently Asked Questions
How long does a sinus infection last?
Acute sinus infections usually last less than 4 weeks, whereas chronic sinusitis continues for more than 12 weeks.
What causes a sinus infection?
Viruses, bacteria, allergies, nasal polyps, and structural abnormalities cause sinus inflammation and blockage.
Why does a sinus infection cause facial pressure?
Blocked sinus cavities increase pressure inside surrounding tissues and produce facial discomfort.
How do doctors diagnose a sinus infection?
Doctors diagnose sinusitis through symptom evaluation, physical examination, nasal endoscopy, and imaging studies when necessary.
What is the difference between acute and chronic sinus infection?
Acute sinusitis lasts fewer than 4 weeks, while chronic sinusitis persists for at least 12 weeks and involves ongoing inflammation.
