Augmentin Suspension Dosing for Adult Acute Bacterial Sinusitis

For an otherwise healthy adult with acute bacterial sinusitis, prescribe Augmentin 875 mg/125 mg orally twice daily for 5–7 days, or use the liquid suspension equivalent of 28 mL of the 125 mg/31.25 mg per 5 mL formulation twice daily if the patient cannot swallow tablets. 1

Confirming the Diagnosis Before Prescribing

Before prescribing any antibiotic, confirm that the patient meets at least one of three diagnostic criteria for acute bacterial rhinosinusitis (ABRS):

Persistent symptoms ≥ 10 days with purulent nasal discharge plus either nasal obstruction or facial pain/pressure/fullness. 2
Severe symptoms ≥ 3–4 consecutive days with fever ≥ 39 °C (102.2 °F), purulent nasal discharge, and facial pain. 2
"Double sickening": initial improvement from a viral upper respiratory infection followed by worsening symptoms within 10 days. 2

Critical context: Approximately 98–99.5% of acute rhinosinusitis cases are viral and resolve spontaneously within 7–10 days without antibiotics. 2 Do not prescribe antibiotics for symptoms lasting <10 days unless the severe criteria above are met. 2

Standard Augmentin Suspension Dosing

Tablet Formulation (Preferred)

Augmentin 875 mg/125 mg tablet orally twice daily for 5–7 days is the first-line regimen for otherwise healthy adults with confirmed ABRS. 3, 1

Liquid Suspension Formulation (For Adults Who Cannot Swallow Tablets)

Use the 125 mg/31.25 mg per 5 mL suspension in place of the 500 mg/125 mg tablet. 1
Dose: 28 mL of the 125 mg/31.25 mg per 5 mL suspension twice daily (equivalent to 875 mg amoxicillin/125 mg clavulanate per dose). 1
Alternative: The 200 mg/28.5 mg per 5 mL or 400 mg/57 mg per 5 mL suspension may be used in place of the 875 mg/125 mg tablet, though specific volume equivalents are not provided in the FDA label. 1

Important: Two 250 mg/125 mg tablets should not be substituted for one 500 mg/125 mg tablet because both contain the same amount of clavulanic acid (125 mg), making them non-equivalent. 1

Treatment Duration: 5–7 Days Is Sufficient

Randomized controlled trials demonstrate that a 5–7 day course of Augmentin achieves clinical cure rates of 74–80%—comparable to traditional 10-day regimens—with no difference in microbiological eradication or relapse. 3
Shorter courses (5–7 days) result in fewer adverse effects, particularly gastrointestinal side effects such as diarrhea. 3
Continue therapy for 5–7 days or until the patient is symptom-free for 7 consecutive days (typically 10–14 days total if symptoms persist beyond day 5). 3

When to Use High-Dose Augmentin (2 g/125 mg Twice Daily)

High-dose Augmentin is indicated when any of the following risk factors are present:

Recent antibiotic use within the past 4–6 weeks. 3
Age >65 years. 3
Daycare exposure (or close contact with daycare children). 3
Moderate-to-severe symptoms. 3
Comorbidities such as diabetes, chronic cardiac/hepatic/renal disease. 3
Immunocompromised state. 3
High local prevalence (>10%) of penicillin-resistant Streptococcus pneumoniae. 3

Rationale: The higher amoxicillin dose improves coverage of penicillin-resistant S. pneumoniae while retaining activity against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis. 3

Monitoring and Reassessment

Early Reassessment (Day 3–5)

If there is no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening symptoms), switch immediately to a respiratory fluoroquinolone such as levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily. 3
Do not extend Augmentin beyond 3–5 days without improvement; delayed escalation increases the risk of complications such as orbital cellulitis, meningitis, or intracranial abscess. 2

Day 7 Reassessment

Persistent or worsening symptoms should prompt confirmation of diagnosis, exclusion of complications, and consideration of imaging or ENT referral. 3

Essential Adjunctive Therapies (Add to All Patients)

Intranasal corticosteroids (e.g., mometasone, fluticasone, budesonide) twice daily significantly reduce mucosal inflammation and accelerate symptom resolution; supported by strong evidence from multiple randomized controlled trials. 3
Saline nasal irrigation 2–3 times daily provides symptomatic relief and aids mucus clearance. 3
Analgesics (acetaminophen or ibuprofen) for pain and fever control. 3

Watchful Waiting (Observation Without Immediate Antibiotics)

Initial observation without antibiotics is appropriate for adults with uncomplicated ABRS who have reliable follow-up. 3
Start antibiotics only if there is no improvement by day 7 or if symptoms worsen at any time. 3
Number needed to treat (NNT): 10–15 patients must receive antibiotics to achieve one additional cure compared with placebo, reflecting the high spontaneous recovery rate. 3

Common Adverse Effects of Augmentin

Diarrhea occurs in 40–43% of patients; severe diarrhea in 7–8%. 3, 4
Gastrointestinal adverse effects are more common with amoxicillin-clavulanate than with other antibiotics. 3
In comparative trials, levofloxacin was better tolerated than Augmentin, with drug-related adverse events occurring in 7.4% vs. 21.2% of patients, respectively. 5

Alternatives for Penicillin-Allergic Patients

Non-Severe (Non-Type I) Penicillin Allergy

Use a second- or third-generation cephalosporin (e.g., cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, cefprozil) for 10 days; cross-reactivity with penicillins is negligible. 3

Severe (Type I/Anaphylactic) Penicillin Allergy

Use a respiratory fluoroquinolone:
- Levofloxacin 500 mg once daily for 10–14 days, or
- Moxifloxacin 400 mg once daily for 10 days.
Predicted efficacy: 90–92% against multidrug-resistant S. pneumoniae and β-lactamase-producing organisms. 3

Suboptimal Alternative

Doxycycline 100 mg once daily for 10 days is acceptable but has lower predicted efficacy (77–81%) and a 20–25% bacteriologic failure rate due to limited activity against H. influenzae. 3

Antibiotics to Avoid in ABRS

Macrolides (e.g., azithromycin): 20–25% resistance in S. pneumoniae and H. influenzae. 3
Trimethoprim-sulfamethoxazole: ≈50% resistance in S. pneumoniae and 27% in H. influenzae. 3
First-generation cephalosporins (e.g., cephalexin): ≈50% of H. influenzae strains produce β-lactamase, rendering them inadequate. 3

Referral to Otolaryngology (ENT)

Refer immediately for any of the following:

No improvement after 7 days of appropriate second-line antibiotic therapy. 3
Worsening symptoms at any point. 3
Suspected complications: severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, or cranial nerve deficits. 3
Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergy, immunodeficiency, or anatomic abnormality. 3

Key Pitfalls to Avoid

Do not extend treatment beyond 7 days without clinical justification; this raises severe diarrhea incidence (≈7–8%) without improving outcomes. 3
Do not prescribe antibiotics for symptoms <10 days unless severe features (fever ≥39 °C with purulent discharge for ≥3 consecutive days) are present. 3
Maintain a minimum 5-day course even if symptoms improve earlier, to prevent relapse and resistance development. 3
Avoid routine imaging (X-ray or CT) for uncomplicated ABRS; up to 87% of viral upper respiratory infections show sinus abnormalities on imaging, leading to unnecessary interventions. 3

What dose of Augmentin (amoxicillin/clavulanate) suspension should an otherwise healthy adult with acute bacterial sinusitis receive?

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