What are the dosages of Augmentin (amoxicillin/clavulanic acid) and doxycycline for treating oral sinusitis infection?

Augmentin and Doxycycline Dosing for Acute Bacterial Sinusitis

For acute bacterial sinusitis, use Augmentin (amoxicillin-clavulanate) 875/125 mg twice daily for 10-14 days as first-line therapy, or doxycycline 100 mg twice daily for 10 days if the patient is penicillin-allergic. 1, 2

First-Line Treatment: Augmentin (Amoxicillin-Clavulanate)

Standard Dosing

• Adults: 875 mg amoxicillin/125 mg clavulanate twice daily for 10-14 days 2, 3, 4
• This dosing is supported by the FDA label and multiple clinical guidelines 4
• The twice-daily regimen is associated with significantly less diarrhea compared to three-times-daily dosing 4, 5

High-Dose Regimen (When Indicated)

• High-dose: 2000 mg amoxicillin/125 mg clavulanate twice daily (or 90 mg/kg/day, not exceeding 2 g every 12 hours) 1, 2
• Use high-dose in patients with:
  • Recent antibiotic use within the past month 1
  • Moderate to severe infection (fever ≥39°C, systemic toxicity) 1
  • Age >65 years 1
  • Geographic regions with >10% penicillin-nonsusceptible S. pneumoniae 1
  • Treatment failure with standard-dose amoxicillin 1, 3
  • Immunocompromised status 1

Important Caveat on High-Dose Efficacy

Recent high-quality evidence shows no significant benefit of high-dose over standard-dose for clinically diagnosed acute sinusitis. A 2021 randomized trial found no difference in improvement rates at day 3 (44.3% standard-dose vs 36.4% high-dose, P=0.35) 6. A 2018 trial showed benefit only with immediate-release (IR) high-dose formulation (52.4% vs 34.4%, P=0.04) but not with extended-release, and IR high-dose caused significantly more severe diarrhea (15.8% vs 4.8%, P=0.048) 7. Given these findings and the increased adverse effects, standard-dose should be preferred for most patients unless specific high-risk factors are present. 6, 7

Alternative for Penicillin Allergy: Doxycycline

Dosing

• Adults: 200 mg on day 1 (100 mg every 12 hours), then 100 mg once daily for days 2-10 8
• Alternative dosing: 100 mg twice daily for 10 days (used in clinical trials for sinusitis) 1
• The FDA label specifies the loading dose approach, but the twice-daily regimen was validated in the European Position Paper trials 1, 8

When to Use Doxycycline

• Penicillin-allergic patients (non-type I hypersensitivity) 1
• Doxycycline is recommended as an alternative agent alongside respiratory fluoroquinolones 1
• Do not use macrolides (azithromycin, clarithromycin) or trimethoprim-sulfamethoxazole as first-line due to high resistance rates (>40% for macrolides, 50% for TMP-SMX against S. pneumoniae) 1

Treatment Duration

• Standard duration: 10-14 days for both Augmentin and doxycycline 1, 2, 3
• Some evidence suggests 5-7 days may be sufficient for uncomplicated cases, but 10-14 days remains the guideline-recommended standard 1, 2
• Continue treatment until symptom-free for 7 days 2, 3

Administration Considerations

Augmentin

• Can be taken with or without food; give with food if gastric irritation occurs 4
• Absorption is not significantly affected by food or milk 4
• Administer with adequate fluids to reduce esophageal irritation risk 4

Doxycycline

• Administer with adequate fluid to reduce esophageal irritation and ulceration risk 8
• Can be given with food or milk if gastric irritation occurs 8
• Absorption is not markedly influenced by food or milk 8

Monitoring and Treatment Response

• Assess clinical response at 3-5 days (72 hours) 3, 9
• If no improvement or worsening at 72 hours:
  • Consider switching to alternative antibiotic 3, 9
  • Re-evaluate diagnosis (may be viral, not bacterial) 3, 9
• If partial response, continue full course of antibiotics 3

Common Pitfalls to Avoid

• Do not treat viral sinusitis with antibiotics - most acute sinusitis is viral and resolves without antibiotics 3, 9
• Do not use high-dose Augmentin routinely - reserve for specific high-risk situations given lack of proven benefit and increased adverse effects 6, 7
• Do not prescribe incomplete courses - failure to complete the full 10-14 day course can lead to treatment failure and relapse 3, 9
• Avoid macrolides and TMP-SMX due to high resistance rates unless no other options exist 1

Adverse Effects

Augmentin

• Diarrhea is the most common adverse effect (40-43% any diarrhea, 7-8% severe diarrhea at day 3) 6
• Twice-daily dosing causes less diarrhea than three-times-daily dosing 4, 5
• High-dose formulations significantly increase severe diarrhea risk 7

Doxycycline

• Esophageal irritation and ulceration (mitigate with adequate fluid intake) 8
• Photosensitivity (counsel patients on sun protection)
• Gastrointestinal upset (can be reduced by taking with food) 8