Best Antibiotics for Bacterial Sore Throat
Penicillin V (phenoxymethylpenicillin), given twice or three times daily for 10 days, remains the first-line antibiotic for bacterial sore throat due to its proven efficacy, safety, narrow spectrum, and low cost. 1
When to Use Antibiotics
Do not prescribe antibiotics for patients with 0-2 Centor criteria (low likelihood of bacterial infection), as most sore throats are viral and antibiotics provide no benefit in these cases 1, 2, 3
Consider antibiotics for patients with 3-4 Centor criteria after discussing that the benefit is modest—shortening symptoms by only 1-2 days 1, 2, 3
Centor criteria include: fever, tonsillar exudates, tender anterior cervical lymphadenopathy, and absence of cough 2, 3
Delayed antibiotic prescribing (waiting 48+ hours) is a valid option that reduces unnecessary use without increasing complication rates 1
First-Line Treatment: Penicillin V
Penicillin V for 10 days is the gold standard because:
- Group A streptococci have shown no resistance to penicillin over five decades 1
- It has the narrowest spectrum, minimizing disruption to normal flora and antibiotic resistance 1
- It is the only antibiotic proven to prevent acute rheumatic fever (though this is now rare in developed countries) 1
- Cost is minimal compared to broader-spectrum alternatives 1, 2
Alternative First-Line: Amoxicillin
Amoxicillin is equally effective to penicillin V and is often preferred in younger children due to better taste and availability as liquid suspension 1
Dosing: 50 mg/kg once daily (maximum 1000 mg) for 10 days in children 2
Avoid amoxicillin in older children and adolescents due to risk of severe rash if Epstein-Barr virus infection (mononucleosis) is present 1
For Penicillin-Allergic Patients
First-generation cephalosporins (e.g., cephalexin) for 10 days if non-anaphylactic penicillin allergy 2
For anaphylactic penicillin allergy, use:
Why NOT to Use Broader-Spectrum Antibiotics
Cephalosporins and macrolides show statistically higher bacterial eradication rates but no clinically meaningful improvement in outcomes compared to penicillin 1:
Meta-analyses show cephalosporins have higher bacterial cure rates (OR 2.29-2.34), but the clinical difference is small and not clinically relevant 1
Azithromycin shows no evidence of differing efficacy compared to penicillin 1, 4
Broader-spectrum antibiotics increase side effects (especially gastrointestinal), disrupt normal microbiota, promote antibiotic resistance, and cost more 1, 4
From 1989-1999, there was an inappropriate increase in use of extended-spectrum macrolides and fluoroquinolones for sore throat, with 68% of patients receiving non-recommended antibiotics 5
Duration of Treatment
The full 10-day course is necessary for maximal bacterial eradication, even though symptoms improve earlier 1, 2
Shorter courses (3-7 days) show inferior outcomes, particularly for 3-day regimens 1
Studies of 5-day cephalosporin courses versus 10-day penicillin show small differences favoring 10 days 1
Common Pitfalls to Avoid
Treating viral pharyngitis with antibiotics—most sore throats (>65%) are viral and do not benefit from antibiotics 2, 3
Using broad-spectrum antibiotics as first-line therapy when narrow-spectrum penicillin is equally effective 4, 5
Prescribing antibiotics to prevent rheumatic fever in low-risk populations—this complication is extremely rare in modern Western settings 1
Stopping treatment early—patients often feel better after 3-5 days but need the full 10-day course for bacterial eradication 1, 2
Special Consideration: Amoxicillin-Clavulanate
Amoxicillin-clavulanate is NOT a first-line agent for initial treatment of streptococcal pharyngitis 4
It is specifically recommended only for retreatment of patients with multiple repeated culture-positive episodes at 40 mg/kg/day in 3 divided doses for 10 days 4
Using it as first-line therapy increases resistance and side effects without additional clinical benefit 4