Sinusitis (sinus infection)

Definition
Sinusitis is inflammation of the paranasal sinuses, usually due to infection, allergy, or irritation, leading to impaired sinus drainage and mucus buildup. It can be acute (lasting <4 weeks), subacute (4–12 weeks), chronic (>12 weeks), or recurrent (≥4 episodes/year).

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Causes

• Viral: Most common (e.g., rhinovirus, influenza, parainfluenza)

• Bacterial: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis

• Fungal: More common in immunocompromised patients (e.g., Aspergillus, Mucor)

• Allergies (allergic rhinitis)

• Nasal polyps, deviated septum

• Dental infections spreading to maxillary sinus

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Risk Factors

• Upper respiratory tract infections

• Allergic rhinitis

• Smoking or secondhand smoke exposure

• Immunodeficiency

• Anatomical nasal abnormalities

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Pathophysiology
Obstruction of sinus ostia → mucus stasis → bacterial overgrowth → inflammation and swelling of mucosa → impaired mucociliary clearance

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Clinical Features

Acute Sinusitis

• Nasal congestion/obstruction

• Purulent nasal discharge (yellow or green)

• Facial pain/pressure (worse bending forward)

• Fever

• Fatigue, cough, postnasal drip

• Reduced smell (hyposmia)

Chronic Sinusitis

• Symptoms ≥12 weeks

• Less severe pain but persistent nasal obstruction, drainage, and reduced smell

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Diagnosis

• Clinical diagnosis in most cases

• Consider imaging (CT sinuses) for chronic/recurrent sinusitis or suspected complications

• Nasal endoscopy for persistent or complicated cases

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Treatment

Acute Viral Sinusitis (most cases)

• Symptomatic management only

• Rest, hydration

• Saline nasal irrigation (e.g., isotonic or hypertonic solution)

• Intranasal corticosteroids (fluticasone 50 mcg/spray, 1–2 sprays per nostril daily) for inflammation

• Analgesia: paracetamol 500–1000 mg every 4–6 hours (max 4 g/day) or ibuprofen 200–400 mg every 6–8 hours as needed

Acute Bacterial Sinusitis (symptoms >10 days or severe with high fever/purulent discharge >3–4 days)

• First-line antibiotic: Amoxicillin-clavulanate 875/125 mg orally twice daily for 5–7 days (adults); in children, 45 mg/kg/day divided BID

• If penicillin allergy: Doxycycline 100 mg orally twice daily for 5–7 days (adults only) or levofloxacin in select cases

• Continue saline irrigation and nasal steroids as above

Chronic Sinusitis

• 4–6 weeks of antibiotics if bacterial (guided by culture)

• Long-term intranasal corticosteroids

• Allergy management

• Endoscopic sinus surgery for refractory cases

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Complications

• Orbital cellulitis or abscess

• Meningitis

• Brain abscess

• Osteomyelitis of frontal bone (Pott’s puffy tumor)

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Quick-Reference Clinical Chart — Sinusitis

Feature	Acute Viral	Acute Bacterial	Chronic
Onset	Sudden after cold	>10 days symptoms or severe onset	>12 weeks
Symptoms	Nasal congestion, clear/mildly colored discharge, facial pressure, low fever	Purulent nasal discharge, facial pain, high fever, worsening after initial improvement	Persistent congestion, drainage, reduced smell
Treatment	Symptomatic only: rest, fluids, saline irrigation, paracetamol 500–1000 mg Q4–6h PRN, ibuprofen 200–400 mg Q6–8h PRN	Amoxicillin-clavulanate 875/125 mg PO BID × 5–7 days + symptomatic measures	Long-term intranasal steroids, culture-guided antibiotics 4–6 weeks, surgery if needed
Complications	Rare	Orbital cellulitis, meningitis, abscess	Chronic sinus disease, orbital or intracranial spread
Prognosis	Full recovery in 1–2 weeks	Good with antibiotics	May require surgery