Amoxicillin Dosage for Strep Throat in Adults
For adults with streptococcal pharyngitis, the recommended dose of amoxicillin is 500 mg orally every 8 hours or 875 mg orally every 12 hours for 10 days. 1, 2
First-Line Treatment Options
Amoxicillin can be administered in two different dosing regimens for adults with strep throat:
- Standard dosing: 500 mg three times daily (every 8 hours) for 10 days
- Higher dose, less frequent: 875 mg twice daily (every 12 hours) for 10 days
Both regimens are equally effective for treating strep throat, with the choice between them often depending on patient preference and convenience 1, 2.
Administration Considerations
- Take amoxicillin at the start of a meal to minimize gastrointestinal intolerance 2
- A full 10-day course is critical to prevent rheumatic fever, even if symptoms resolve earlier 1
- Patients are considered non-contagious after 24 hours of appropriate antibiotic therapy 1
Alternative for Penicillin-Allergic Patients
For patients with penicillin allergy, alternative treatments include:
- Non-anaphylactic allergy: Cephalexin 500 mg twice daily for 10 days
- Immediate hypersensitivity/anaphylactic allergy:
- Clindamycin 300 mg three times daily for 10 days
- Azithromycin 500 mg once daily for 5 days
- Clarithromycin 250 mg twice daily for 10 days 1
Dosage Adjustment for Renal Impairment
For patients with severe renal impairment:
- GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours
- GFR <10 mL/min: 500 mg or 250 mg every 24 hours
- Hemodialysis: 500 mg or 250 mg every 24 hours plus additional dose during and at end of dialysis 2
Clinical Pearls and Pitfalls
- Common pitfall: Stopping antibiotics early when symptoms improve. Emphasize to patients the importance of completing the full 10-day course to prevent complications like rheumatic fever 1
- Important: Once-daily dosing of amoxicillin (1000 mg daily) has been studied and shown to be effective 3, 4, 5, but the FDA-approved dosing remains either twice or three times daily 2
- Diagnostic consideration: Before prescribing antibiotics, confirm strep throat diagnosis with rapid antigen detection test (RADT) and/or throat culture, especially in patients with 3-4 Centor criteria (fever, tonsillar exudates, tender anterior cervical adenopathy, absence of cough) 1
- Symptom management: NSAIDs are first-line for pain relief, along with warm salt water gargles and throat lozenges 1
Remember that while simplified regimens may improve compliance, the standard FDA-approved dosing remains either 500 mg three times daily or 875 mg twice daily for a full 10 days to ensure complete eradication of the infection and prevention of complications.