Maximum Dose of Amoxicillin
The maximum daily dose of oral amoxicillin for adults is 4 grams per day, regardless of patient size or weight. 1
Adult Dosing Limits
- The standard maximum daily dose of oral amoxicillin for adults is 4 grams per day, as established by the American Academy of Otolaryngology-Head and Neck Surgery 1
- When combined with clavulanic acid, the maximum dose remains 4 grams of amoxicillin component with 250 mg of clavulanate per day 1
- For respiratory infections requiring higher coverage against resistant organisms, high-dose amoxicillin is defined as 4 g/day 1
- Serum levels of amoxicillin increase linearly with dose, as gastrointestinal absorption is not a limiting factor 1
Pediatric Dosing Limits
- For children, high-dose amoxicillin is defined as 90 mg/kg/day, not to exceed 4000 mg/day 1
- For Group A streptococcal pharyngitis, the maximum dose is 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) 1
- When combined with clavulanate, high-dose amoxicillin for children is 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate (in two divided doses) 1
Clinical Considerations
- The upper limit of amoxicillin is often determined by gastrointestinal tolerability rather than toxicity concerns 1
- The difference in adverse effects between lower and higher doses is generally negligible, though higher doses may increase risk of gastrointestinal side effects 1
- For severe infections requiring high-dose therapy, the maximum remains 4 g/day for adults, regardless of body weight 1
- In infective endocarditis treatment, ampicillin (closely related to amoxicillin) has a maximum daily dose of 12 g, but this is for intravenous administration only 2
Formulation Considerations
- Pharmacokinetically enhanced formulations of amoxicillin/clavulanate have been developed to maintain therapeutic plasma concentrations for longer periods, but still adhere to the 4 g/day maximum 3
- The 16:1 ratio formulation of amoxicillin/clavulanate (2000/125 mg) was designed to optimize time above MIC while staying within safe dosing parameters 3
- Clavulanic acid is more strongly associated with gastrointestinal side effects than amoxicillin, which can limit the maximum daily dose of the combination 4
Common Pitfalls
- Assuming that larger patients can receive doses exceeding 4 g/day - this is incorrect as the maximum remains 4 g/day regardless of patient size 1
- Using first-generation cephalosporins instead of amoxicillin for certain infections where amoxicillin is more effective 1
- Failing to adjust dosing in patients with renal impairment, which may require lower maximum doses 1
- Confusing oral amoxicillin maximum doses with intravenous ampicillin/amoxicillin doses, which can be higher in certain severe infections 2