Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Viral etiologies are the most common cause. Sinusitis presents with facial pain over the affected sinus and purulent rhinorrhea. Diagnosis is usually clinical and management is supportive, although it may require antibiotics.

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Epidemiology and Etiology


  • Incidence: 1 of 7–8 people per year
  • Occurs in up to 80% of patients with uncomplicated upper respiratory infections (URIs)
  • Bacterial sinusitis is only found in 0.5%–2% of cases
  • Peak annual incidence coincides with peak of viral URIs in fall/winter months
  • Higher incidence in women and in those aged 45–64 years


  • Predisposing factors:
    • Anatomic abnormalities of the paranasal sinuses or nasal cavity (deviation in nasal septum, concha bullosa, bony spurs, nasal polyp, choanal atresia)
    • Impairment of ciliary function (cystic fibrosis, primary ciliary dyskinesia, immunodeficiency)
    • Allergic and vasomotor rhinitis
    • Recurrent URIs
    • Asthma and allergies
    • Dental disease
    • Immunodeficiency
    • Older age
    • Smoking
    • Cocaine abuse
    • Air travel
    • Atmospheric pressure change exposure (e.g., deep sea diving)
    • Swimming
    • Foreign body in the nasal cavity
  • Acute: lasts ≤ 4 weeks
    • Viral (most common): rhinovirus, coronavirus, influenza virus, adenovirus, parainfluenza virus
    • Bacterial: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, Escherichia coli, Klebsiella
      • S. pnuemoniae and H. influenzae are responsible for 75% of cases
  • Chronic: lasts over 12 weeks; characterized by prolonged inflammation of the sinuses; occasionally associated with immunodeficiency disorders
    • Fungal: Aspergillus, Rhizopus oryzae
    • Bacterial: S. aureus (often methicillin-resistant S. aureus) and anaerobic organisms (Prevotella, Porphyromonas, Fusobacterium, and Peptostreptococcus spp.)



  • Inoculation via direct contact with the conjunctiva or nasal mucosa
  • Viral replication can be detected via viral levels in nasal secretions within 8–10 hours
  • Symptoms can occur after the first day of inoculation


  • Most important pathophysiological change: obstruction of sinus drainage 
  • Normal metachronous (sequential) movement of mucous toward the natural ostia of the sinuses is usually disrupted by mucosal inflammation → stasis
  • Ciliary function impairment leads to a reduction in mucus drainage → stasis
  • Stasis of secretions inside the sinuses leads to a proliferation of microorganisms
  • Alterations in the composition and quantity of mucus can also contribute to infection; increased mucus production is seen with asthma, rhinitis, and viral URIs

Clinical Presentation

General manifestations

  • Nasal congestion and obstruction
  • Mucopurulent or purulent nasal discharge
  • Headache
  • Facial pain or heaviness over the affected sinus (increases with bending forward)
    • Maxillary sinuses: over the cheeks
    • Frontal sinuses: lower forehead
    • Ethmoidal sinuses: nasal bridge or between/behind the eyes
  • Fever
  • Maxillary tooth discomfort and other facial pain
  • General malaise and myalgia

Viral sinusitis

Viral sinusitis usually presents in a milder form and lasts 7–10 days.

Bacterial sinusitis

  • Persists for > 10 days without clinical improvement
  • Biphasic pattern: may initially improve, then worsens after 5–6 days (“double worsening”)
  • Presents with more severe symptoms:
    • High fever
    • Intense facial pain 
    • Hyposmia or anosmia
    • Halitosis
    • Cough
    • Ear pain, pressure, fullness, hearing loss, or tinnitus

Fungal sinusitis

Fungal sinusitis usually presents chronically, with atypical symptoms (epistaxis, dyspnea, and black/brown nasal secretions).

Complications and/or associated conditions

  • Acute otitis media
  • Pharyngitis
  • Meningitis
  • Pneumonia
  • Subperiosteal/intracranial abscess
  • Osteomyelitis (usually of the frontal bone)
  • Preseptal/orbital cellulitis
  • Septic cavernous sinus thrombosis


Diagnosis is usually based on clinical symptoms.

  • Uncomplicated sinusitis: < 4 weeks of purulent nasal discharge + nasal obstruction or facial pain/pressure/fullness or both
  • Complicated sinusitis: When signs and symptoms extend beyond paranasal sinuses and nasal cavity, urgent evaluation is required.
    • Signs: severe/persistent headache, vision changes, periorbital edema, abnormal extraocular movements with or without pain, altered mental status, meningeal signs, signs of increased intracranial pressure

To differentiate viral sinusitis from bacterial sinusitis:

  • Viral rhinosinusitis is diagnosed clinically when symptoms last 7–10 days and do not worsen.
  • Bacterial rhinosinusitis is diagnosed clinically when symptoms last > 10 days or are of a biphasic pattern (see “double worsening,” above) and are more severe in nature. Requires antibiotics for resolution

Laboratory tests

  • Indicated if no response to treatment or worsening is observed
  • Leukocytosis is rarely seen.
  • May help determine the underlying cause:
    • Allergic rhinitis confirmed with a radioallergosorbent test, allergen skin test, or smear of nasal secretions showing eosinophilia
    • Sweat chloride test for cystic fibrosis


Presence of more than 104 colony-forming units/mL on bacterial culture is confirmatory for bacterial sinusitis in children.


  • Not recommended unless complicated sinusitis arises
  • Skull X-rays show decreased transparency of sinus and air-fluid levels.
  • Computed tomography is the modality of choice and shows mucoperiosteal thickening, air-fluid levels, and soft tissue extension in case of complications (e.g., orbital cellulitis).
  • Nasal endoscopy may be used to exclude structural lesions.


Only needed if infection recurs or if there is no response to different empiric therapies.


General supportive care

  • Acetaminophen or nonsteroidal anti-inflammatory drugs should be given for facial pain and, if present, fever.

Viral sinusitis

  • Aims only to provide symptomatic relief, as viral sinusitis is self-limiting
  • Nasal lavage with hypertonic NaCl solution 
  • Decongestants (e.g., xylometazoline nasal spray) or sympathomimetics (e.g., pseudoephedrine) 
  • Antihistamines (e.g., loratadine) if concurrent allergy symptoms are present
  • Intranasal steroids (e.g., fluticasone) to relieve mucosal swelling/facial pain
  • Mucolytics (e.g., guaifenesin) can thin secretions and promote drainage

Bacterial sinusitis

  • First-line: amoxicillin, with or without clavulanate for 5–10 days
  • Second-line:
    • IV ceftriaxone is used for children who are unable to tolerate oral medication.
    • Oxycycline, levofloxacin, or moxifloxacin are used in case of penicillin allergy.
    • Levofloxacin, moxifloxacin, or clindamycin are used if symptoms persist > 14 days or no improvement is seen within the first 3 days of treatment.
  • Chronic bacterial sinusitis: broad-spectrum aminopenicillin + beta-lactamase inhibitor 
  • Decongestants and antihistamines are not recommended.

Fungal sinusitis

  • Antifungal therapy (e.g., amphotericin B)
  • Management of immunocompromising conditions (e.g., AIDS, HIV, cancer, etc.)
  • If the infection is chronic and invasive, it may require surgical debridement of necrotic tissue.

Clinical Relevance

The following are potential underlying conditions or differential diagnoses of sinusitis:

  • Cystic fibrosis: an autosomal recessive disorder caused by mutation of the CFTR gene, which leads to defective chloride channels and hyperviscosity of exocrine gland secretions
  • Primary ciliary dyskinesia: an autosomal recessive disease associated with sinusitis, situs inversus, recurrent respiratory infections, and bronchiectasis, among other abnormalities
  • Dental abscess: a collection of pus in the pulp of a tooth that can spread to local or regional structures, including the gums, facial bones, tongue, and facial muscles
  • Foreign nasal body: common in children < 5 years old. Often involves food items or small toys. Presents with unilateral rhinorrhea that can become foul-smelling or purulent, signs of nasal obstruction, or epistaxis
  • Migraine: a type of headache characterized by recurrent, debilitating episodes that are typically unilateral, throbbing and/or pulsatile in quality, and frequently accompanied by nausea, vomiting, and sensitivity to light and sound
  • Rhinitis: an inflammation of the nasal mucosa, classified into allergic, non-allergic, and infectious
  • Asthma: a chronic inflammatory disease of the respiratory system characterized by bronchial hyperresponsiveness, episodic exacerbation, and reversible airflow obstruction. 
  • Otitis media: an infection of the middle ear that typically follows an upper respiratory tract infection in children < 5 years old. Most commonly caused by S. pneumoniae. Presents with otalgia and fever. Examination shows a bulging tympanic membrane.
  • Granulomatosis with polyangiitis: an antineutrophil cytoplasmic antibody–associated vasculitis leading to inflammation of small- and medium-sized blood vessels. Results in damage to several organ systems of the body, most often the respiratory tract and kidneys.

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