What is the recommended duration of amoxicillin treatment for an adult or child over 3 months of age with a bacterial sinus infection and no severe penicillin allergy?

Duration of Amoxicillin for Bacterial Sinus Infection

Adults: 5-7 Days

For adults with uncomplicated acute bacterial sinusitis, amoxicillin should be given for 5-7 days 1. This shorter duration has comparable effectiveness to traditional 10-14 day courses while reducing adverse events, improving compliance, and minimizing antibiotic resistance 1, 2.

Evidence Supporting Shorter Duration in Adults

• The IDSA 2012 guideline explicitly recommends 5-7 days for uncomplicated ABRS in adults (weak recommendation, low-moderate quality evidence) 1
• Meta-analysis of 12 randomized controlled trials involving 4,430 adult patients found no difference in clinical success between short-course (3-7 days) and long-course (6-10 days) treatment 2
• Five-day regimens specifically showed fewer adverse events compared to 10-day courses (OR 0.79,95% CI 0.63-0.98) 2
• Multiple studies demonstrate that 5-day courses of various antibiotics achieve 74-80% clinical cure rates, equivalent to 10-day regimens 3, 4

Dosing for Adults

• Mild disease: Amoxicillin 500 mg twice daily for 5-7 days 1, 5
• Moderate-to-severe disease: Amoxicillin 875 mg twice daily for 5-7 days 1, 5
• High-dose for resistant organisms: Amoxicillin 2 g twice daily for 5-7 days 1

Children: 10-14 Days

For children with acute bacterial sinusitis, amoxicillin must be given for 10-14 days 1, 6, 7. This longer duration is necessary despite the adult data showing equivalence of shorter courses.

Why Children Require Longer Treatment

• The IDSA guideline explicitly states that children require 10-14 days of treatment despite the adult data supporting shorter courses 1
• Treatment must continue for at least 7 days after the child becomes symptom-free 6, 7, 8
• For any infection caused by Streptococcus pyogenes, at least 10 days of treatment is mandatory to prevent acute rheumatic fever 1, 9, 8

Pediatric Dosing

• Standard dose (age ≥2 years, no recent antibiotics, no daycare): 45 mg/kg/day divided twice daily 6, 7, 8
• High dose (age <2 years, daycare attendance, recent antibiotics, or high local resistance): 80-90 mg/kg/day divided twice daily 1, 6, 7
• Maximum daily dose should not exceed adult dosing 9

Critical Reassessment Timepoints

Adults

• Reassess at 3-5 days: If no improvement or worsening, switch to amoxicillin-clavulanate or alternative therapy 1, 5
• Reassess at 7 days: If symptoms persist, reconfirm diagnosis and consider second-line therapy 1, 5

Children

• Reassess at 72 hours: If worsening or no improvement, switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) 1, 6, 7
• This 72-hour threshold is evidence-based: only 9% of placebo-treated children who failed at day 3 showed improvement between days 3-10 without intervention 6

When to Use Amoxicillin-Clavulanate Instead

Amoxicillin-clavulanate is preferred over plain amoxicillin as initial therapy in both adults and children 1. However, if plain amoxicillin is chosen:

Switch to Amoxicillin-Clavulanate If:

• No improvement after 3-5 days (adults) or 72 hours (children) 1, 6
• Recent antibiotic use within past 4-6 weeks 1, 5
• Moderate-to-severe disease at presentation 1, 5
• Age <2 years (children) 6, 7
• Daycare attendance (children) 6, 7
• High local prevalence of β-lactamase-producing organisms 1, 5

Common Pitfalls to Avoid

• Do not extend adult treatment to 10-14 days routinely: This increases adverse events without improving outcomes 2, 4
• Do not shorten pediatric treatment to 5-7 days: Children require the full 10-14 days despite adult data 1, 6
• Do not continue ineffective therapy beyond reassessment timepoints: Failure at 72 hours (children) or 3-5 days (adults) predicts continued failure without intervention 1, 6
• Do not stop antibiotics when symptoms resolve in children: Continue for 7 additional days after symptom resolution to complete at least 10 days total 6, 7, 8

Adjunctive Therapies to Enhance Outcomes

• Intranasal corticosteroids: Strongly recommended for all patients to reduce inflammation and improve drainage 1, 5
• Saline nasal irrigation: Provides symptomatic relief and removes mucus 1, 5
• Analgesics (acetaminophen, NSAIDs): For pain and fever management 1, 5
• Adequate hydration and warm facial packs: Supportive measures 5