Amoxicillin Dosing for Strep Throat in Adults
For an otherwise healthy adult with strep throat, amoxicillin should be dosed at 500 mg orally twice daily for 10 days, or alternatively 1000 mg (1 gram) once daily for 10 days. 1, 2, 3
Standard Dosing Regimens
The American Heart Association and Infectious Diseases Society of America endorse two equally effective amoxicillin regimens for adults with Group A streptococcal pharyngitis:
- 500 mg twice daily for 10 days - This is the most commonly prescribed regimen with strong evidence for efficacy 1, 2, 3
- 1000 mg (1 gram) once daily for 10 days - This once-daily option has been proven equally effective as twice-daily dosing and may improve compliance 1, 4
Both regimens provide equivalent bacteriologic eradication rates and clinical outcomes, with the once-daily option offering the advantage of simplified dosing without compromising efficacy 4.
Critical Treatment Duration
The full 10-day course is absolutely essential - even if symptoms resolve within 3-4 days, completing the entire course is necessary to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever 1, 2, 3. Shortening the course by even a few days dramatically increases treatment failure rates and the risk of rheumatic fever 5.
Why Amoxicillin Over Penicillin V?
While penicillin V remains the gold standard (250 mg four times daily or 500 mg twice daily for 10 days), amoxicillin offers practical advantages 1, 2, 3:
- Better compliance - Twice-daily or once-daily dosing is easier to follow than penicillin V's three to four times daily schedule 4
- Equivalent efficacy - Amoxicillin achieves comparable bacteriologic and clinical cure rates to penicillin V 1, 4
- Lower cost - Amoxicillin is inexpensive and widely available 2, 3
Alternative for Compliance Concerns
If you doubt the patient's ability to complete a 10-day oral course, intramuscular benzathine penicillin G 1.2 million units as a single dose is the preferred alternative, ensuring complete treatment with one administration 1, 2, 3.
Common Pitfalls to Avoid
- Do not prescribe shorter courses - Despite symptom resolution, the full 10 days is required to prevent rheumatic fever 1, 5, 2
- Do not use once-daily dosing below 1000 mg - Studies show that 1000 mg once daily is effective, but lower once-daily doses (such as 500 mg) have higher failure rates 6
- Do not routinely order follow-up cultures - Post-treatment throat cultures are unnecessary for asymptomatic patients who completed therapy 2, 3
When Patient Becomes Non-Contagious
Patients are generally considered non-contagious after 24 hours of antibiotic therapy, allowing return to work or normal activities 2.