What is the recommended dose of amoxicillin (amoxicillin) for treating bacterial infections?

Recommended Dosage of Amoxicillin for Bacterial Infections

The recommended dose of amoxicillin for treating bacterial infections in adults is 250-500 mg every 8 hours or 500-875 mg every 12 hours, with specific dosing depending on infection severity and type. 1

Adult Dosing Guidelines

Standard Adult Dosing

• Mild to moderate infections:
  • 500 mg every 12 hours OR 250 mg every 8 hours 1
• Severe infections:
  • 875 mg every 12 hours OR 500 mg every 8 hours 1

Infection-Specific Dosing

• Lower respiratory tract infections:
  • 875 mg every 12 hours OR 500 mg every 8 hours (regardless of severity) 1
• Skin and soft tissue infections (erysipeloid):
  • 500 mg three times daily (every 8 hours) for 7-10 days 2
• Animal bite infections:
  • Amoxicillin-clavulanate 875/125 mg twice daily preferred over amoxicillin alone 2

Pediatric Dosing Guidelines

Standard Pediatric Dosing (≥3 months and <40 kg)

• Mild to moderate infections:
  • 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours 1
• Severe infections:
  • 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 1

Infants <12 weeks (3 months)

• Maximum recommended dose: 30 mg/kg/day divided every 12 hours 1
  • This lower dose accounts for incompletely developed renal function in this age group

Special Populations

Renal Impairment (Adults and Children >40 kg)

• GFR 10-30 mL/min:
  • 500 mg or 250 mg every 12 hours (based on infection severity) 1
• GFR <10 mL/min:
  • 500 mg or 250 mg every 24 hours (based on infection severity) 1
• Hemodialysis patients:
  • 500 mg or 250 mg every 24 hours plus additional dose during and after dialysis 1
• Important: Patients with GFR <30 mL/min should NOT receive the 875 mg dose 1

Administration Considerations

• Take amoxicillin at the start of a meal to minimize gastrointestinal intolerance 1
• Treatment should generally continue for 48-72 hours beyond symptom resolution 1
• For Streptococcus pyogenes infections, treat for at least 10 days to prevent acute rheumatic fever 1

Dosing Frequency Options

Research has shown that twice-daily dosing of amoxicillin is as effective as three-times-daily dosing for many infections:

• A Cochrane review demonstrated comparable clinical cure rates between once/twice daily versus three times daily dosing regimens 3
• A study of lower respiratory tract infections found amoxicillin-clavulanate given every 12 hours (875/125 mg) was as effective as every 8 hours (500/125 mg) with similar safety profiles 4

Common Pitfalls and Caveats

• Underdosing: Using standard doses for severe infections may lead to treatment failure, especially with less susceptible organisms
• Duration errors: Streptococcal infections require minimum 10-day treatment to prevent rheumatic fever 1
• Renal adjustment errors: Using 875 mg doses in patients with severe renal impairment can lead to toxicity 1
• Resistance concerns: Higher doses (e.g., 4 g/day) may be needed for resistant respiratory pathogens, particularly in areas with high rates of penicillin-resistant pneumococci 2
• Formulation confusion: Oral suspensions come in different concentrations (125 mg/5 mL and 250 mg/5 mL), which can lead to dosing errors if not clearly specified 1

Remember that amoxicillin should only be used for infections proven or strongly suspected to be caused by susceptible bacteria to reduce the development of drug-resistant bacteria 1.