What are the standard dosing, treatment duration, renal dose adjustments, contraindications, adverse effects, and alternative therapies for amoxicillin‑clavulanate (Augmentin) in adults and children?

Amoxicillin-Clavulanate (Augmentin) Dosing & Clinical Guidelines

Standard Adult Dosing

For most respiratory tract infections in adults, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 5–7 days. 1

• For mild-to-moderate infections without risk factors, the standard dose is 500 mg/125 mg three times daily or 875 mg/125 mg twice daily for 7–10 days. 1
• For severe pneumonia requiring hospitalization, use 1.2 g IV three times daily, then switch to oral formulation as soon as clinically appropriate. 1

High-Dose Adult Regimen (Risk Factors Present)

When risk factors are present—recent antibiotic use (past 4–6 weeks), age > 65, daycare exposure, moderate-to-severe symptoms, comorbidities, immunocompromised status, or geographic areas with > 10% penicillin-resistant S. pneumoniae—prescribe amoxicillin 2 g + clavulanate 125 mg twice daily. 1

• This high-dose regimen achieves 90–92% predicted clinical efficacy against drug-resistant Streptococcus pneumoniae. 1
• Treatment duration for acute bacterial rhinosinusitis is 5–7 days in adults, which is as effective as 10-day courses with fewer adverse effects. 1

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Pediatric Dosing (≥ 3 Months, < 40 kg)

For children with acute otitis media or acute bacterial rhinosinusitis, prescribe high-dose amoxicillin-clavulanate 90 mg/kg/day (amoxicillin component) + 6.4 mg/kg/day (clavulanate), divided into 2 doses for 10 days. 2, 1, 3

• This high-dose regimen provides a 14:1 ratio of amoxicillin to clavulanate, which is less likely to cause diarrhea than other formulations. 2, 3
• The maximum daily dose is 4000 mg/day of amoxicillin. 1

Standard-Dose Pediatric Regimen (Uncomplicated Cases)

• For uncomplicated infections without risk factors, use 45 mg/kg/day (amoxicillin component) + 6.4 mg/kg/day (clavulanate), divided into 2 doses for 10 days. 1, 3

High-Dose Indications in Children

Use the high-dose regimen (90 mg/kg/day) when any of the following risk factors are present: 2, 1, 3

• Age < 2 years
• Daycare attendance
• Recent antibiotic use (past 30 days)
• Incomplete Haemophilus influenzae type b vaccination
• Geographic area with > 10% penicillin-resistant S. pneumoniae
• Moderate-to-severe illness
• Concurrent purulent conjunctivitis (otitis-conjunctivitis syndrome)
• Bilateral acute otitis media in children 6–23 months

Age-Based Oral Suspension Dosing (Standard Infections)

• < 1 year (1–12 months): 2.5 mL of 125/31 suspension three times daily 3
• 1–6 years: 5 mL of 125/31 suspension three times daily 3
• 7–12 years: 5 mL of 250/62 suspension three times daily 3
• ≥ 12 years: 1 tablet (250/125 mg) three times daily 3

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Intravenous Dosing (Pediatric)

For severe infections requiring IV therapy in children, administer 30 mg/kg (amoxicillin component) three times daily (every 8 hours), infused over 15–30 minutes. 4

• The standard IV dose range is 100–200 mg/kg/day divided every 6–8 hours, with a maximum of 4000 mg/day. 4
• IV therapy is indicated for severe infections, inability to tolerate oral medications, or complicated intra-abdominal infections. 4

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Minimum Age for Use

Amoxicillin-clavulanate may be initiated in children ≥ 3 months of age when bacterial infection is suspected or confirmed. 3, 5

• Safety and efficacy data are robust for children ≥ 3 months but remain limited for infants < 3 months. 3
• For infants < 3 months with suspected serious bacterial infection, IV regimens (ampicillin + gentamicin or cefotaxime) are preferred over oral amoxicillin-clavulanate. 3

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Treatment Duration by Indication

• Acute bacterial rhinosinusitis (adults): 5–7 days 1
• Acute bacterial rhinosinusitis (children): 10–14 days 1, 3
• Acute otitis media (children < 6 years): 10 days 3
• Community-acquired pneumonia (children): 10 days 3
• Bronchiectasis exacerbations (adults): 14 days 1

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Clinical Reassessment & Treatment Failure

Reassess at 48–72 hours in children and 3–5 days in adults; if no improvement or worsening occurs, switch to high-dose amoxicillin-clavulanate or a respiratory fluoroquinolone (adults) or escalate to high-dose amoxicillin-clavulanate (children). 1, 3

• Clinical improvement (reduced pain, fever, irritability) should begin within 48–72 hours. 3
• Persistent or worsening symptoms at 7 days in adults require diagnostic reconsideration, possible imaging, and ENT referral. 1

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Renal Dose Adjustments

In patients with renal insufficiency, prolong the dosing interval according to creatinine clearance to avoid accumulation, as both amoxicillin and clavulanic acid are renally eliminated. 3

• For children with altered renal function, significantly reduce the dose. 3

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Contraindications

• Absolute contraindication: History of serious hypersensitivity reaction (anaphylaxis, Stevens-Johnson syndrome) to amoxicillin, clavulanate, or any β-lactam antibiotic. 5
• Relative contraindication: History of cholestatic jaundice or hepatic dysfunction associated with prior amoxicillin-clavulanate use. 5

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Adverse Effects

The most common adverse effects are gastrointestinal: diarrhea (25% vs. 15% placebo), nausea, vomiting, and diaper dermatitis (51% vs. 35% placebo in infants). 3, 6

• The 14:1 ratio formulation (90/6.4 mg/kg/day) causes less diarrhea than other amoxicillin-clavulanate preparations. 2, 3
• Diarrhea is generally less frequent with twice-daily dosing than three-times-daily dosing. 6
• Skin rash occurs in approximately 3–5% of patients. 3
• Serious adverse events are rare; a large postmarketing study reported only 3.6% total adverse events with no serious events. 6

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Alternative Therapies (Penicillin Allergy)

Adults

• Doxycycline or respiratory fluoroquinolones (levofloxacin or moxifloxacin) 1

Children (Non-Type I Penicillin Allergy)

• Clindamycin (30–40 mg/kg/day in 3 divided doses) plus a third-generation oral cephalosporin (cefdinir 14 mg/kg/day, cefuroxime 30 mg/kg/day, or cefpodoxime 10 mg/kg/day) 2, 1
• Cefdinir, cefuroxime, cefpodoxime, and ceftriaxone are highly unlikely to cross-react with penicillin allergy based on distinct chemical structures. 2

Treatment Failure After 48–72 Hours

• Ceftriaxone 50 mg/kg IM or IV daily for 3 days 2
• If second antibiotic fails, perform tympanocentesis/drainage or seek infectious disease consultation. 2

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Key Prescribing Pitfalls to Avoid

• Do not prescribe antibiotics for symptom duration < 10 days unless severe features are present (fever ≥ 39°C with purulent nasal discharge for ≥ 3 consecutive days); 98–99.5% of acute rhinosinusitis cases are viral. 1
• Verify suspension concentration (125/31 vs. 250/62) before calculating volume to avoid dosing errors. 3
• Do not underdose: Using standard doses when high-dose therapy is indicated leads to treatment failure with resistant organisms. 3
• Avoid subtherapeutic doses: They fail to achieve adequate serum and tissue concentrations and promote antimicrobial resistance. 3
• For patients ≥ 40 kg, use adult dosing rather than pediatric weight-based calculations to avoid dosing errors. 1

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Adjunctive Therapies

• Intranasal corticosteroids (mometasone, fluticasone, budesonide) twice daily reduce mucosal inflammation and speed symptom resolution. 1
• Saline nasal irrigation 2–3 times daily provides symptomatic relief and enhances mucus clearance. 1
• Analgesics (acetaminophen or ibuprofen) for pain and fever control. 1

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Pharmacokinetic Considerations

• Approximately 50–70% of amoxicillin and 25–40% of clavulanic acid are excreted unchanged in urine during the first 6 hours. 5
• Neither component is highly protein-bound: clavulanic acid ≈ 25%, amoxicillin ≈ 18%. 5
• Amoxicillin diffuses readily into most body tissues and fluids, including middle ear fluid, with the exception of brain and spinal fluid. 5
• High-dose amoxicillin (80–90 mg/kg/day) achieves middle ear fluid concentrations that exceed the MIC for intermediately resistant S. pneumoniae (penicillin MIC 0.12–1.0 µg/mL) and many highly resistant serotypes (penicillin MIC ≥ 2 µg/mL). 3, 7

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Pregnancy & Lactation

• Pregnancy Category B: Reproduction studies in rats and mice at doses up to 1,200 mg/kg/day revealed no evidence of harm to the fetus, but there are no adequate and well-controlled studies in pregnant women; use only if clearly needed. 5
• Lactation: Ampicillin-class antibiotics are excreted in human milk; exercise caution when administering to nursing women. 5