Recommended Dose of Augmentin for Adult Sinusitis
For adults with acute bacterial sinusitis, prescribe amoxicillin-clavulanate (Augmentin) 875 mg/125 mg twice daily for 5-7 days, or use high-dose formulation (2000 mg amoxicillin/125 mg clavulanate twice daily) if the patient has risk factors for resistant bacteria.
Dosing Algorithm
Standard-Dose Augmentin (First-Line for Most Patients)
- Dose: 875 mg/125 mg twice daily
- Duration: 5-7 days (up to 10 days if symptoms persist)
- Indications: Uncomplicated acute bacterial sinusitis in patients without resistance risk factors 1
High-Dose Augmentin (For High-Risk Patients)
- Dose: 2000 mg amoxicillin/125 mg clavulanate twice daily (maximum 2 g per dose)
- Duration: 5-10 days
- Use when ANY of these risk factors present 1:
- Antibiotic use within past month
- Age >65 years
- Recent hospitalization
- Daycare exposure
- Severe symptoms (fever ≥39°C/102.2°F with purulent discharge for ≥3 days)
- Geographic area with high pneumococcal resistance (>10%)
- Immunocompromised status
- Diabetes or chronic cardiac/hepatic/renal disease
- Smoker or household smoker
- Failed initial amoxicillin therapy 2
Clinical Context
The 2015 AAO-HNS guideline emphasizes that amoxicillin-clavulanate should be considered over amoxicillin alone when bacterial resistance is likely 1. The high-dose formulation (90 mg/kg/day amoxicillin component, not exceeding 2 g every 12 hours) provides adequate coverage against penicillin-nonsusceptible S. pneumoniae and β-lactamase-producing H. influenzae 2.
Recent evidence from 2026 challenges routine use of amoxicillin-clavulanate: A large retrospective study of 234,608 adults found no difference in treatment failure rates between standard-dose amoxicillin-clavulanate versus amoxicillin alone (3.0% vs 3.1%), but amoxicillin-clavulanate was associated with higher rates of yeast infections (1.1% vs 0.8%) and C. difficile infections (0.04% vs 0.02%) 3. This suggests that for uncomplicated cases without resistance risk factors, plain amoxicillin may be preferable.
Duration Considerations
Multiple studies support shorter courses (5-7 days) as equally effective as 10-day regimens for uncomplicated acute bacterial sinusitis, with fewer adverse events 1, 4. The traditional recommendation of treating "until 7 days after symptom resolution" typically results in 10-14 day courses 2.
Common Pitfalls to Avoid
- Don't prescribe antibiotics for viral rhinosinusitis: Only use when symptoms persist >10 days without improvement, worsen after initial improvement (double-sickening), or are severe (fever ≥39°C with purulent discharge for ≥3 consecutive days) 5, 1
- Don't use macrolides or trimethoprim-sulfamethoxazole: Resistance rates exceed 40% for S. pneumoniae 1
- Don't automatically choose high-dose: Reserve for patients with specific risk factors to minimize adverse effects 3
- Reassess at 3-5 days: If no improvement, consider switching antibiotics or alternative diagnosis 2
Adverse Effects
Diarrhea is the most common side effect, occurring in 10-15% of patients. High-dose formulations increase this risk (15.8% vs 4.8% with standard-dose) 6. Gastrointestinal side effects are more common with 10-day courses versus 5-day courses 1.