Upper Dose Limits of Oral Amoxicillin

Adult Dosing Limits

The maximum daily dose of oral amoxicillin for adults is 4 grams per day, with specific formulations allowing higher doses when combined with clavulanic acid, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
High-dose amoxicillin is defined as 4 g/day for respiratory infections requiring higher coverage against resistant organisms, as recommended by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
High-dose amoxicillin/clavulanate is defined as 4 g of amoxicillin with 250 mg of clavulanate per day for adults, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2

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), as recommended by the American Academy of Family Physicians 3, 4
For respiratory tract infections with resistant pathogens, high-dose amoxicillin for children is defined as 90 mg/kg/day, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
For uncomplicated urinary tract infections in children, amoxicillin can be dosed at 40-90 mg/kg/day in 2-3 divided doses (maximum 4000 mg/day), as recommended by the Journal of Microbiology, Immunology and Infection 5

For children, high-dose amoxicillin/clavulanate is 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate (in two divided doses), according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
For chronic carriers of Group A Streptococcus, amoxicillin/clavulanate can be dosed at 40 mg amoxicillin per kg per day in three doses (maximum 2,000 mg amoxicillin per day), as recommended by the American Academy of Family Physicians 3, 4

The upper limit of amoxicillin is often determined by gastrointestinal tolerability rather than toxicity concerns, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 2
Serum levels of amoxicillin increase linearly with dose, as gastrointestinal absorption is not a limiting factor, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
The difference in adverse effects between lower and higher doses is generally negligible, though higher doses may increase risk of gastrointestinal side effects, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 2

Using first-generation cephalosporins instead of amoxicillin for conditions like Lyme disease, as they are ineffective against B. burgdorferi, as recommended by the Infectious Diseases Society of America 6

For children with high risk of resistant organisms, dosing may be increased to 80-90 mg/kg/day of the amoxicillin component (maximum 2g per dose), as recommended by the American Academy of Pediatrics 7