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

Amoxicillin Dosage and Treatment Duration for Bacterial Infections

The recommended dosage of amoxicillin for bacterial infections varies by infection type, with standard adult dosing of 500 mg-1g orally every 8 hours or 875 mg every 12 hours for 5-7 days for most respiratory tract infections. 1

Adult Dosing Guidelines

Respiratory Tract Infections

• For low severity community-acquired pneumonia (CAP): Amoxicillin 500 mg-1g orally every 8 hours for 5-7 days 1
• For moderate severity CAP: Amoxicillin 500 mg-1g orally every 8 hours or 875 mg every 12 hours for 5-7 days 1
• For upper respiratory tract infections: 750-1750 mg/day in divided doses every 8-12 hours 2
• For lower respiratory tract infections: 875 mg every 12 hours or 500 mg every 8 hours 2

Genitourinary Tract Infections

• For uncomplicated urinary tract infections: 500 mg every 12 hours or 250 mg every 8 hours for 3-7 days 2, 3
• For severe urinary tract infections: 875 mg every 12 hours or 500 mg every 8 hours 2

Skin and Skin Structure Infections

• For mild/moderate infections: 500 mg every 12 hours or 250 mg every 8 hours 2
• For severe infections: 875 mg every 12 hours or 500 mg every 8 hours 2

H. pylori Infection (Adults only)

• Triple therapy: 1 gram amoxicillin, 500 mg clarithromycin, and 30 mg lansoprazole, all given twice daily for 14 days 2
• Dual therapy: 1 gram amoxicillin and 30 mg lansoprazole, each given three times daily for 14 days 2

Pediatric Dosing Guidelines

Children ≥3 Months and <40 kg

• For mild/moderate ear, nose, throat, skin, and genitourinary infections: 25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours 2
• For severe ear, nose, throat, skin, and genitourinary infections: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours 2
• For lower respiratory tract infections (mild/moderate or severe): 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours 2

Children <3 Months

• Due to incompletely developed renal function: Maximum 30 mg/kg/day divided every 12 hours 2

Pediatric Community-Acquired Pneumonia

• For children with pneumonia: Amoxicillin is the reference treatment, with dosing of 80-100 mg/kg/day in three daily intakes for children weighing less than 30 kg 1
• For children with pneumonia over 3 years of age: If pneumococcal infection is suspected, use amoxicillin as described above; if atypical bacteria are suspected, consider macrolides 1

Pediatric Acute Otitis Media

• High-dose amoxicillin (80-90 mg/kg/day in 2 divided doses) is recommended as first-line treatment 1
• For children who have taken amoxicillin in the previous 30 days or with concurrent conjunctivitis: High-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component in 2 divided doses) 1

Treatment Duration by Infection Type

• Community-acquired pneumonia: 5-7 days for low to moderate severity 1
• Acute otitis media: Standard duration (typically 10 days) 1
• Acute bacterial sinusitis in children: 10 days 1
• Streptococcal pharyngitis: Minimum 10 days to prevent acute rheumatic fever 2
• Urinary tract infections: 3-7 days 4, 3
• H. pylori infection: 14 days 2

Special Considerations

Dosing in Renal Impairment

• For GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours, depending on infection severity 2
• For GFR <10 mL/min: 500 mg or 250 mg every 24 hours, depending on infection severity 2
• Patients with severe renal impairment (GFR <30 mL/min) should NOT receive the 875 mg dose 2

Antimicrobial Resistance Considerations

• In communities with high prevalence of non-susceptible S. pneumoniae (>10%), consider high-dose amoxicillin therapy (80-90 mg/kg/day in 2 divided doses) 1
• For patients with risk factors for beta-lactamase-producing organisms, consider amoxicillin-clavulanate instead of amoxicillin alone 1

Recent Evidence on Treatment Duration

• Recent studies suggest that shorter courses (3-5 days) of amoxicillin may be as effective as longer courses (7-10 days) for uncomplicated community-acquired pneumonia in children 5, 6
• However, it is recommended to continue treatment for at least 48-72 hours beyond the time that the patient becomes asymptomatic 2

Common Pitfalls and Caveats

• Failure to adjust dosing for renal impairment can lead to toxicity 2
• Inadequate treatment duration for streptococcal infections may lead to acute rheumatic fever; minimum 10 days treatment is recommended 2
• Not considering local resistance patterns when selecting dosage can lead to treatment failure 1
• Using amoxicillin alone when beta-lactamase-producing organisms are suspected may result in treatment failure 1
• Not recognizing when higher doses are needed for resistant organisms 1