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

Amoxicillin Dosing Recommendations

For most common infections in adults, amoxicillin 500 mg three times daily or 875 mg twice daily is the standard dose, while pediatric dosing ranges from 20-90 mg/kg/day divided into 2-3 doses depending on infection severity and site. 1

Adult Dosing

Standard Infections (Mild to Moderate)

• Skin/soft tissue, ear/nose/throat, genitourinary infections: 500 mg every 12 hours OR 250 mg every 8 hours 1
• Severe infections (same sites): 875 mg every 12 hours OR 500 mg every 8 hours 1
• Lower respiratory tract infections (all severities): 875 mg every 12 hours OR 500 mg every 8 hours 1

Specific Conditions

• Uncomplicated UTI: 500 mg PO/IV every 8 hours for 3-7 days 2
• Dental/jaw infections: 500 mg orally three times daily for 7-10 days 3
• Erysipeloid: 500 mg three times daily for 7-10 days 2
• Animal/human bites: Amoxicillin-clavulanate 875/125 mg twice daily is preferred over amoxicillin alone 2

H. pylori Eradication

• Triple therapy: 1 gram amoxicillin + 500 mg clarithromycin + 30 mg lansoprazole, all twice daily for 14 days 1
• Dual therapy: 1 gram amoxicillin + 30 mg lansoprazole, both three times daily for 14 days 1

Pediatric Dosing (≥3 Months and <40 kg)

By Infection Severity

Mild to moderate infections (ear/nose/throat, skin, genitourinary):

• 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours 1

Severe infections (same sites) and all lower respiratory tract infections:

• 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 1

High-Dose Amoxicillin for Pneumococcal Infections

For community-acquired pneumonia or acute otitis media with suspected resistant Streptococcus pneumoniae:

• 90 mg/kg/day in 2 divided doses (preferred) OR 45 mg/kg/day in 3 divided doses 2
• Maximum daily dose: 4000 mg/day 2

This high-dose regimen is critical because standard dosing may be inadequate for penicillin-resistant pneumococci (MIC ≥2.0 μg/mL) 2. However, local resistance patterns should guide this decision—communities with low prevalence of resistant strains may not require routine high-dose therapy 4.

Neonates and Infants <3 Months

• Maximum dose: 30 mg/kg/day divided every 12 hours 1
• This reduced dosing accounts for immature renal function 2

Specific Pediatric Conditions

• Impetigo: 25 mg/kg/day of amoxicillin component (if using amoxicillin-clavulanate) in 2 divided doses 2
• Group A Streptococcus infections: 50-75 mg/kg/day in 2 doses 2
• Haemophilus influenzae (β-lactamase negative): 75-100 mg/kg/day in 3 doses 2

Renal Impairment Dosing

Adults and children >40 kg with severe renal dysfunction:

• 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

Administration Considerations

• Take at the start of meals to minimize gastrointestinal intolerance 1
• Minimum treatment duration: 48-72 hours beyond symptom resolution or bacterial eradication 1
• Streptococcus pyogenes infections: Minimum 10 days to prevent acute rheumatic fever 1
• Oral suspension: Shake well before use; refrigeration preferred but not required; discard after 14 days 1

Common Pitfalls to Avoid

Do not substitute two 250 mg tablets for one 500 mg tablet when using amoxicillin-clavulanate—this results in excessive clavulanate dosing and increased gastrointestinal side effects 3

Larger children often receive inadequate dosing: Studies show children >60 kg frequently receive <40 mg/kg/day when high-dose therapy is indicated, as clinicians hesitate to exceed "adult maximum doses" 5. For severe infections requiring high-dose therapy, do not cap the dose prematurely based on weight alone.

Antibiotics are adjunctive for dental abscesses: Surgical drainage or extraction is mandatory—antibiotics alone will fail regardless of dose 3

Twice-daily dosing is equally effective as three-times-daily for most infections: Studies demonstrate comparable pharmacokinetics and clinical outcomes with 25 mg/kg twice daily versus 15 mg/kg three times daily in children with pneumonia, improving compliance 6, 7. However, for resistant pneumococcal infections, higher total daily doses (80-90 mg/kg/day) divided twice daily are necessary 2.