What is the recommended amoxicillin dosage for treating community-acquired pneumonia in adults and children?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: October 21, 2026 • View editorial policy

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question

Amoxicillin Dosage for Community-Acquired Pneumonia

For adults without comorbidities, use amoxicillin 1 gram every 8 hours; for children, use 90 mg/kg/day divided into 2 doses (maximum 4 g/day). These high-dose regimens provide optimal coverage against Streptococcus pneumoniae, including strains with reduced penicillin susceptibility.

Adults

Outpatient Treatment

For previously healthy adults without comorbidities, amoxicillin 1 gram every 8 hours is the preferred first-line therapy 1. This recommendation is based on studies demonstrating efficacy of high-dose oral amoxicillin for inpatient CAP, which reasonably extends to outpatients since they are generally lower risk. The high dose overcomes potential resistance issues with pneumococcus while maintaining an excellent safety profile 1.

For adults with comorbidities (chronic heart, lung, liver, or renal disease; diabetes; alcoholism; malignancies; asplenia), combination therapy is preferred:

  • Amoxicillin 1 gram every 8 hours PLUS a macrolide (azithromycin or clarithromycin), OR
  • Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily, moxifloxacin 400 mg daily) 1

FDA-Approved Dosing

The FDA label confirms dosing for lower respiratory tract infections 2:

  • Adults and children >40 kg: 875 mg every 12 hours OR 500 mg every 8 hours for mild/moderate to severe infections
  • Children <40 kg: 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours

Children

Outpatient Treatment (Age ≥3 months)

The preferred dose is amoxicillin 90 mg/kg/day divided into 2 doses 3. This high-dose regimen is critical for:

  • Children <5 years with presumed bacterial pneumonia 3
  • Children ≥5 years with bacterial CAP (maximum 4 g/day) 3

The 90 mg/kg/day dosing (versus the older 45 mg/kg/day) provides adequate coverage against pneumococcal strains with intermediate penicillin resistance, which is increasingly common 3.

Inpatient Treatment

For hospitalized children who are fully immunized and in areas with minimal penicillin resistance:

  • Ampicillin or penicillin G is preferred 3
  • Alternatives: ceftriaxone or cefotaxime 3

For children not fully immunized or in areas with significant penicillin resistance:

  • Ceftriaxone (50-100 mg/kg/day every 12-24 hours) or cefotaxime (150 mg/kg/day every 8 hours) 3

Infants <3 months

Maximum dose is 30 mg/kg/day divided every 12 hours due to immature renal function 2. This is a critical safety consideration that prevents drug accumulation.

Duration of Therapy

Recent evidence supports shorter treatment courses when patients achieve clinical stability:

  • 3 days for non-severe CAP with clinical stability at day 3 4, 5
  • 5 days when stability achieved by day 5 4
  • 7 days for other uncomplicated CAP 1, 4

A high-quality pediatric trial demonstrated that 3-day amoxicillin treatment was non-inferior to 7-day treatment for clinical cure, with faster resolution of cough in the 7-day arm (10 vs 12 days) but similar rates of antibiotic retreatment (12.5% in both groups) 6. Multiple meta-analyses confirm that 5-day courses are as effective as 10-day courses for uncomplicated pediatric CAP 7.

Special Populations

Renal Impairment

  • GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours 2
  • GFR <10 mL/min: 500 mg or 250 mg every 24 hours 2
  • Hemodialysis: Additional dose during and after dialysis 2
  • Do NOT use 875 mg dose if GFR <30 mL/min 2

Key Considerations

Common pitfalls to avoid:

  • Using standard doses (45 mg/kg/day in children, 500 mg TID in adults) instead of high doses—this risks treatment failure with resistant pneumococcus
  • Continuing antibiotics beyond clinical stability—this increases resistance without improving outcomes
  • Using amoxicillin-clavulanate as first-line when plain amoxicillin suffices—the clavulanate adds cost and GI side effects without benefit for typical CAP pathogens

When to add macrolide coverage:

  • Children ≥5 years where atypical pathogens (Mycoplasma, Chlamydophila) cannot be distinguished clinically 3
  • Adults with comorbidities 1
  • Suspected Legionella (though rare in outpatients) 1

Administration: Take at the start of meals to minimize GI intolerance 2.

References

Related Questions

In an otherwise healthy adult with community‑acquired pneumonia, is high‑dose amoxicillin still the appropriate first‑line oral therapy, and what dosing regimen should be used?
What amoxicillin (Amoxil) dose and treatment duration are recommended for a 6‑year‑old male child with a chest infection?
What is the recommended duration of high‑dose amoxicillin (1 g three times daily) for an otherwise healthy adult with community‑acquired pneumonia?
What is the recommended adult dosing of amoxicillin‑clavulanate (including high‑dose and alternative regimens) for treating community‑acquired pneumonia in an otherwise healthy adult?
What is the recommended outpatient antibiotic regimen for a 5‑year‑old child (≈20 kg) with community‑acquired pneumonia?
What is the most common type of anemia in a female patient with systemic lupus erythematosus?
For a septic patient with a wound containing gram‑positive cocci and gram‑negative bacilli, is cefepime (2 g IV every 8 hours, dose‑adjusted for renal function) an appropriate empiric antibiotic, and should it be combined with an anaerobic agent?
What are examples of potassium-sparing diuretics?
In a patient who has completed a 7‑day therapeutic course of enoxaparin for pulmonary embolism, should apixaban be initiated with a loading dose or can it be started directly without a loading dose?
Can D-dimer and the Wells score be used to confidently exclude pulmonary embolism and avoid CT pulmonary angiography (CTPA)?
What do the dilution ratios 2:10 and 1:40 indicate in antibody titer testing?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.