What is the typical dosage and treatment duration of Amoxicillin (amoxicillin) for bacterial infections?

Amoxicillin Dosing and Treatment Duration for Bacterial Infections

For most common bacterial infections in adults and children over 3 months weighing more than 40 kg, amoxicillin should be dosed at 500 mg every 12 hours or 250 mg every 8 hours for mild-to-moderate infections, and 875 mg every 12 hours or 500 mg every 8 hours for severe infections, with treatment continued for a minimum of 48-72 hours beyond symptom resolution. 1

Adult and Pediatric Dosing (≥3 Months and >40 kg)

Mild-to-Moderate Infections

• Ear/nose/throat, skin/skin structure, and genitourinary tract infections: 500 mg every 12 hours OR 250 mg every 8 hours 1
• Treatment duration: minimum 48-72 hours beyond clinical improvement or bacterial eradication 1

Severe Infections

• All sites (including lower respiratory tract): 875 mg every 12 hours OR 500 mg every 8 hours 1
• Lower respiratory tract infections require this higher dosing regardless of severity 1

Pediatric Dosing (<40 kg, ≥3 Months)

Weight-Based Dosing

• 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 <3 Months

• Maximum dose: 30 mg/kg/day divided every 12 hours (due to immature renal function) 1
• No dosing recommendations exist for infants with renal impairment 1

Critical Duration Considerations

Streptococcus pyogenes Infections

• Mandatory minimum 10-day treatment to prevent acute rheumatic fever, regardless of clinical improvement 1
• This is non-negotiable for any strep throat or streptococcal infection 1

Extended Therapy

• Some infections require several weeks of treatment 1
• Clinical and bacteriological follow-up may be needed for months after therapy cessation 1

Special Populations

Renal Impairment (Adults and Pediatric >40 kg)

• GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours 1
• GFR <10 mL/min: 500 mg or 250 mg every 24 hours 1
• Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and after dialysis 1
• Critical caveat: Patients with GFR <30 mL/min should NOT receive the 875 mg dose 1

H. pylori Eradication (Adults Only)

• Triple therapy: Amoxicillin 1 gram + clarithromycin 500 mg + lansoprazole 30 mg, all twice daily for 14 days 1
• Dual therapy (clarithromycin allergy/resistance): Amoxicillin 1 gram + lansoprazole 30 mg, both three times daily for 14 days 1

Administration Pearls

• Take at the start of meals to minimize gastrointestinal intolerance 1
• Oral suspension must be shaken well before each use 1
• Reconstituted suspension expires after 14 days; refrigeration preferred but not required 1