What is the first‑line therapy for uncomplicated acute bacterial sinusitis in adults and children?

First-Line Therapy for Uncomplicated Acute Bacterial Sinusitis

Amoxicillin with or without clavulanate is the first-line antibiotic for uncomplicated acute bacterial sinusitis in both adults and children, but watchful waiting without antibiotics is equally appropriate for most patients with mild-to-moderate symptoms when follow-up is assured. 1, 2

Initial Management Decision: Antibiotics vs. Watchful Waiting

The most important clinical decision is whether to prescribe antibiotics at all. For adults with uncomplicated acute bacterial rhinosinusitis (ABRS), clinicians should offer either watchful waiting or initial antibiotic therapy 1. This choice matters because:

• Most patients improve spontaneously—86% cure rate with placebo by 7-15 days
• Antibiotics only modestly increase cure rates to 91% (number needed to treat: 11-15 patients)
• Antibiotics cause adverse events in 13 more people per 100 treated 1

When to Choose Watchful Waiting:

• Mild symptoms (mild pain, temperature <38.3°C/101°F)
• Reliable follow-up is assured
• Patient can start antibiotics if no improvement by 7 days or worsening at any time 1

When to Start Immediate Antibiotics:

Adults:

• Severe symptoms at onset (high fever ≥39°C/102°F with purulent discharge for 3-4 consecutive days)
• Moderate-to-severe illness
• Risk factors for resistant bacteria 1, 3

Children:

• Severe presentation: fever ≥102.2°F (39°C) with purulent nasal discharge for ≥3 consecutive days
• Worsening symptoms after initial improvement
• Persistent symptoms >10 days without improvement 2, 4

For children with persistent (not severe) illness, observation for 3 days without antibiotics is also an option 4.

First-Line Antibiotic Choice

Adults:

Standard dose amoxicillin (500 mg three times daily or 875 mg twice daily) for 5-10 days is first-line for most adults 1.

Use high-dose amoxicillin-clavulanate (2 g twice daily or 90 mg/kg/day) instead when:

• Antibiotic use in past month
• Geographic area with >10% penicillin-nonsusceptible S. pneumoniae
• Moderate-to-severe infection
• Age >65 years
• Recent hospitalization
• Immunocompromised
• Close contact with daycare children
• Smoker or household smoker 3

Children:

For children ≥2 years with mild-to-moderate illness, no daycare attendance, and no recent antibiotics:

• Amoxicillin 45 mg/kg/day in 2 divided doses 2
• In communities with >10% nonsusceptible S. pneumoniae: 80-90 mg/kg/day in 2 divided doses (max 2 g/dose) 2

For children <2 years, in daycare, or with recent antibiotic use, or moderate-to-severe illness:

• High-dose amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses (max 2 g/dose) 2

For children unable to tolerate oral medication:

• Single dose ceftriaxone 50 mg/kg IV/IM, then switch to oral if improved at 24 hours 2

Penicillin Allergy Alternatives

Adults:

• Doxycycline OR
• Respiratory fluoroquinolone (levofloxacin or moxifloxacin) 1, 3
• For non-type I hypersensitivity: clindamycin plus third-generation cephalosporin (cefixime or cefpodoxime) 3

Children:

• Cefdinir, cefuroxime, or cefpodoxime 2, 4

Do NOT use: Macrolides (azithromycin, clarithromycin) or trimethoprim-sulfamethoxazole due to high resistance rates (>40% for macrolides, 50% for TMP-SMX against S. pneumoniae) 4, 3

Treatment Duration

5-7 days is as effective as 10 days with fewer side effects 1. The traditional 10-day course is acceptable but shorter courses reduce adverse events (odds ratio 0.79) 3.

Reassessment for Treatment Failure

If symptoms worsen after 48-72 hours or fail to improve after 3-5 days of antibiotics, reassess the patient 5. At this point:

• Confirm ABRS diagnosis
• Exclude complications
• Switch antibiotic if already on treatment
• Start antibiotic if on watchful waiting 1

Adjunctive Symptomatic Treatment

Regardless of antibiotic decision, offer:

• Acetaminophen or ibuprofen for pain/fever
• Saline nasal irrigation
• Decongestants (nasal spray ≤3 days; oral acceptable)
• Intranasal corticosteroids (especially with allergic rhinitis history) 1, 5

Avoid: Antihistamines and oral steroids—they don't relieve symptoms and have side effects 1

Critical Pitfalls

1. Don't image routinely—CT/MRI not indicated unless complications suspected 1, 6
2. Don't use nasopharyngeal cultures—unreliable; only direct sinus aspiration or endoscopic middle meatus cultures are valid 5
3. Recognize that antibiotics provide marginal benefit—only 5-11 more people per 100 cured faster, while 13 per 100 experience adverse effects 1, 7
4. Complications are rare but serious—suspect if severe headache, visual changes, proptosis, altered mental status, or focal neurologic signs develop 4