What is the recommended dose of amoxicillin for an adult?

Recommended Dosage of Amoxicillin for Adults

The standard adult dosage of amoxicillin is 250-500 mg three times daily or 500-875 mg twice daily, with specific dosing dependent on the infection being treated. 1

Standard Dosing Regimens

• For mild to moderate infections (ear/nose/throat, skin/skin structure, genitourinary tract): 500 mg every 12 hours or 250 mg every 8 hours 1
• For severe infections (ear/nose/throat, skin/skin structure, genitourinary tract): 875 mg every 12 hours or 500 mg every 8 hours 1
• For lower respiratory tract infections (mild/moderate or severe): 875 mg every 12 hours or 500 mg every 8 hours 1

Condition-Specific Dosing

• For community-acquired pneumonia: 1 g every 8 hours 2
• For Group A streptococcal pharyngitis: 500 mg twice daily or 250 mg four times daily for 10 days 2
• For H. pylori infection (as part of triple therapy): 1 g twice daily for 14 days 1
• For H. pylori infection (as part of dual therapy): 1 g three times daily for 14 days 1
• For acute bacterial sinusitis: Standard dose of 500 mg three times daily or 875 mg twice daily; high-dose of 4 g/day may be considered in areas with high prevalence of penicillin-resistant S. pneumoniae 2

Dosing in Special Populations

Renal Impairment

• GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours (depending on infection severity) 1
• GFR less than 10 mL/min: 500 mg or 250 mg every 24 hours (depending on infection severity) 1
• Hemodialysis: 500 mg or 250 mg every 24 hours with additional dose both during and at end of dialysis 1

Administration Considerations

• Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 1
• For oral suspension, shake well before using 1
• Treatment should generally continue for a minimum of 48-72 hours beyond symptom resolution 1
• For streptococcal infections, a minimum of 10 days of treatment is recommended to prevent acute rheumatic fever 1, 2

Important Clinical Considerations

• Amoxicillin is contraindicated in patients with history of serious hypersensitivity reactions to penicillins or other beta-lactam antibiotics 1
• Common adverse effects include diarrhea, nausea, vomiting, and rash 1
• For infections caused by beta-lactamase-producing organisms, amoxicillin-clavulanate should be used instead of amoxicillin alone 2
• High-dose amoxicillin (4 g/day) may be necessary for areas with high prevalence of penicillin-resistant S. pneumoniae 2
• Recent studies suggest that the standard dose of amoxicillin-clavulanate may be insufficient for certain severe infections, particularly those caused by Enterobacteriaceae with higher MICs 3

Monitoring

• No specific baseline monitoring is required for amoxicillin therapy 2
• Patients should be monitored for hypersensitivity reactions, including anaphylaxis and severe cutaneous adverse reactions 1
• Monitor for Clostridioides difficile-associated diarrhea, which can range from mild to severe 1

By following these dosing guidelines, clinicians can optimize amoxicillin therapy for adult patients while minimizing the risk of treatment failure and adverse effects.