What is the recommended dosage and treatment duration of Amoxicillin for bacterial infections?

Amoxicillin Dosage and Treatment Duration for Bacterial Infections

For bacterial infections, amoxicillin is typically dosed at 500 mg three times daily or 875 mg twice daily for adults, with treatment duration ranging from 5-10 days depending on the infection type and severity. 1

Adult Dosing Recommendations

By Infection Type:

• Ear/Nose/Throat, Skin/Skin Structure, Genitourinary Tract:

  • Mild/Moderate: 500 mg every 12 hours or 250 mg every 8 hours
  • Severe: 875 mg every 12 hours or 500 mg every 8 hours 1

• Lower Respiratory Tract:

  • 875 mg every 12 hours or 500 mg every 8 hours regardless of severity 1

• Erysipeloid:

  • 500 mg four times daily or 500 mg three times daily for 7-10 days 2

• Community-Acquired Pneumonia:

  • Outpatient (low severity): 500 mg-1g three times daily for 5-7 days 2

• Uncomplicated Urinary Tract Infections:

  • 500 mg orally/IV every 8 hours for 3-7 days 2

Special Situations:

• H. pylori Infection (Adults only):

  • Triple therapy: 1 gram twice daily (with clarithromycin and lansoprazole) for 14 days
  • Dual therapy: 1 gram three times daily (with lansoprazole) for 14 days 1

• Human Bite Infections:

  • Amoxicillin-clavulanate 875/125 mg twice daily 2

Pediatric Dosing Recommendations

• Children <40 kg:

  • Mild/Moderate infections: 25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours
  • Severe infections: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours 1

• Children <12 weeks:

  • Maximum 30 mg/kg/day divided every 12 hours due to incompletely developed renal function 1

Treatment Duration Guidelines

Treatment duration should be tailored to the specific infection:

• General bacterial infections: Continue for a minimum of 48-72 hours beyond symptom resolution 1
• Streptococcal infections: Minimum 10 days to prevent acute rheumatic fever 1
• Community-acquired pneumonia: 5-7 days 2, 3
• Erysipeloid: 7-10 days 2
• Urinary tract infections: 3-7 days 2
• H. pylori infection: 14 days 1

Dosage Adjustments

Renal Impairment (Adults and Children >40 kg):

• GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours
• GFR <10 mL/min: 500 mg or 250 mg every 24 hours
• Hemodialysis: 500 mg or 250 mg every 24 hours plus additional dose during and after dialysis 1

Administration Considerations

• Take at the start of a meal to minimize gastrointestinal intolerance 1
• For oral suspension, shake well before using and refrigerate (preferable but not required) 1
• Unused reconstituted suspension must be discarded after 14 days 1

Clinical Pearls and Caveats

• Amoxicillin should only be used for infections proven or strongly suspected to be caused by susceptible bacteria to reduce development of drug-resistant bacteria 1
• For infections caused by bacteria with intermediate susceptibility to amoxicillin, follow the recommendations for severe infections 1
• Research suggests that twice-daily dosing (875 mg) is as effective as three-times-daily dosing (500 mg) for lower respiratory tract infections, which may improve adherence 4
• High-dose vs. standard-dose amoxicillin-clavulanate showed no significant difference in treatment outcomes for acute sinusitis in adults 5
• Once-daily amoxicillin has been shown to be non-inferior to twice-daily dosing for streptococcal pharyngitis in children 6

By following these evidence-based dosing recommendations and treatment durations, clinicians can optimize therapeutic outcomes while minimizing the risk of antimicrobial resistance and adverse effects.