Dosing for Severe Sinus Infection in Adults
For a severe sinus infection in an adult, prescribe high-dose amoxicillin-clavulanate 2000 mg/125 mg (or 875 mg/125 mg twice daily) orally twice daily for 5-7 days. 1
Why High-Dose Amoxicillin-Clavulanate for Severe Infection
Severe sinusitis requires amoxicillin-clavulanate rather than amoxicillin alone because moderate-to-severe symptoms indicate higher risk of resistant organisms. 1 The American Academy of Otolaryngology-Head and Neck Surgery specifically identifies "moderate to severe symptoms of ABRS" as a key factor prompting use of amoxicillin-clavulanate instead of amoxicillin monotherapy. 1
Specific High-Dose Indications
High-dose formulations are recommended when patients have: 1
- Severe infection (systemic toxicity, fever ≥39°C/102°F, threat of suppurative complications)
- Recent antibiotic use within the past month
- Age >65 years
- Geographic regions with high rates (>10%) of penicillin-nonsusceptible S. pneumoniae
- Immunocompromised status
Exact Dosing Regimens
Standard Severe Infection Dosing
875 mg amoxicillin/125 mg clavulanate twice daily is the FDA-approved dose for severe respiratory tract infections. 2 This provides adequate coverage for most cases of severe sinusitis. 3, 4
High-Dose Regimen for Resistant Organisms
2000 mg amoxicillin/125 mg clavulanate twice daily (or 90 mg/kg/day divided twice daily, not exceeding 2 g per dose) is recommended for high-risk patients. 1 The IDSA guideline specifically endorses this high-dose regimen for adults at risk of amoxicillin-resistant organisms. 1
Treatment Duration
5-7 days is the recommended duration for uncomplicated severe ABRS in adults. 1 This shorter course is supported by the IDSA 2012 guideline, which found comparable efficacy to 10-14 day courses with reduced adverse events. 1
- The American Academy of Otolaryngology notes that systematic reviews found no difference in clinical success between 3-7 days versus 6-10 days of therapy. 1
- Most traditional guidelines recommended 10-14 days, but newer evidence supports shorter courses. 1, 3
Critical Clinical Pitfalls
Do Not Underdose
Two 250 mg/125 mg tablets cannot substitute for one 500 mg/125 mg tablet because both contain the same 125 mg of clavulanate—doubling the clavulanate dose unnecessarily increases diarrhea risk. 2
Assess Response at 72 Hours
If symptoms worsen or fail to improve after 48-72 hours, switch to alternative therapy (respiratory fluoroquinolone like levofloxacin or moxifloxacin) or reevaluate the diagnosis. 1
Adverse Effects
Severe diarrhea occurs in 7-16% of patients on high-dose regimens compared to 5-7% on standard doses. 5 Counsel patients about this risk but emphasize treatment completion for severe infections.
Penicillin Allergy Alternatives
For true penicillin allergy: 1
- Respiratory fluoroquinolones (levofloxacin or moxifloxacin) are preferred alternatives
- Doxycycline is an acceptable option
- Avoid macrolides (>40% S. pneumoniae resistance) and TMP-SMX (high resistance rates)
Renal Dosing Adjustments
For patients with renal impairment: 2
- GFR <30 mL/min: Do not use the 875 mg/125 mg dose
- GFR 10-30 mL/min: 500 mg/125 mg every 12 hours
- GFR <10 mL/min or hemodialysis: 500 mg/125 mg every 24 hours, with additional dose during and after dialysis
Evidence Quality Note
The 2015 American Academy of Otolaryngology guideline and 2012 IDSA guideline provide the strongest evidence base for these recommendations. 1 Recent research (2018-2021) comparing high-dose versus standard-dose showed mixed results—one study found benefit for immediate-release high-dose formulations, while another found no difference—but both confirmed the safety profile. 5, 6 Given the severe nature of the infection described, the high-dose regimen remains justified per guideline recommendations.