What is the typical dosage and treatment duration for Amoxicillin (Dymox)?

Amoxicillin (Dymox) Dosing and Duration

For most common bacterial infections in adults, amoxicillin should be dosed at 500 mg twice daily or 250 mg three times daily for mild-to-moderate infections, with treatment duration of 5-10 days depending on the infection type. 1

Standard Adult Dosing

Typical dosing regimens:

• Mild-to-moderate infections: 500 mg every 12 hours OR 250 mg every 8 hours 1
• Severe infections or resistant organisms: 875 mg every 12 hours OR 500 mg every 8 hours 1
• High-dose therapy (for resistant S. pneumoniae): Up to 4 g/day in divided doses (maximum 1 g every 12 hours) 1

Pediatric Dosing (≥3 months and <40 kg)

Standard pediatric regimens:

• Mild-to-moderate infections: 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours 2
• Severe infections: 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 2
• High-dose therapy (resistant organisms): 90 mg/kg/day in 2 divided doses 1

For infants <3 months, the maximum dose is 30 mg/kg/day divided every 12 hours due to immature renal function 2

Treatment Duration by Indication

Infection-specific durations:

• Sinusitis: 10-14 days 1
• Streptococcal pharyngitis: Minimum 10 days to prevent rheumatic fever 2, 3
• Community-acquired pneumonia: 3-7 days (shorter courses non-inferior for uncomplicated cases) 4
• Dental infections: 5-7 days when combined with clavulanate 5
• Skin/soft tissue infections: 5-10 days 2
• H. pylori eradication: 14 days (1 g twice daily with clarithromycin and PPI, or 1 g three times daily with PPI alone) 2

General principle: Continue treatment 48-72 hours beyond symptom resolution or bacterial eradication 2

Dosing Adjustments for Renal Impairment

Renal dosing modifications (adults and children >40 kg):

• GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours 2
• GFR <10 mL/min: 500 mg or 250 mg every 24 hours 2
• Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and after dialysis 2
• Important: Do NOT use 875 mg dose if GFR <30 mL/min 2

High-Dose Considerations for Resistant Organisms

The emergence of penicillin-resistant S. pneumoniae (25-50% of strains) necessitates higher dosing in many cases 1. High-dose amoxicillin (90 mg/kg/day in children, 4 g/day in adults) overcomes relative resistance by maintaining adequate time above MIC 1. This approach is particularly important for respiratory tract infections where resistant pneumococci are common 1.

Administration Guidelines

Key administration points:

• Take at the start of meals to minimize gastrointestinal intolerance 2
• Oral suspension must be shaken well before each use 2
• Reconstituted suspension expires after 14 days; refrigeration preferred but not required 2

Common Pitfalls to Avoid

• Do not use amoxicillin monotherapy for acne (should be avoided per guidelines) 1
• Do not prescribe for viral upper respiratory infections (strongly discouraged) 1
• Do not use 875 mg dose in severe renal impairment (GFR <30 mL/min) 2
• Do not underdose streptococcal pharyngitis (must complete full 10-day course to prevent rheumatic fever) 2
• Do not rely solely on antibiotics for dental abscesses (surgical drainage is primary treatment) 5

Special Populations

Pregnancy: Category B - generally safe 1

Breastfeeding: Minimal risk to infant, compatible with breastfeeding 1

Pediatric use: Safety and efficacy established for children ≥3 months 1