What is the first line treatment and dosage for strep throat?

First-Line Treatment for Strep Throat

Penicillin or amoxicillin is the first-line treatment for strep throat in non-allergic patients, with amoxicillin 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days being the preferred regimen due to better palatability in children and equivalent efficacy. 1, 2

Primary Treatment Regimens

For Non-Penicillin-Allergic Patients

Oral Penicillin/Amoxicillin Options:

• Amoxicillin (preferred in children due to taste): 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 2
• Penicillin V: Children: 250 mg twice or three times daily for 10 days; Adolescents/Adults: 250 mg three to four times daily OR 500 mg twice daily for 10 days 3, 4
• Intramuscular benzathine penicillin G: 1.2 million units as a single dose (preferred when compliance with oral therapy is uncertain) 3

The once-daily amoxicillin regimen carries a "strong, high" recommendation and may improve adherence compared to multiple daily dosing 1, 2. Penicillin remains the drug of choice based on its narrow spectrum, low adverse event rate, and modest cost 3.

For Penicillin-Allergic Patients

The choice depends on the type of allergic reaction:

Non-Immediate (Non-Anaphylactic) Allergy:

• First-generation cephalosporins (preferred): Cephalexin 20 mg/kg twice daily (maximum 500 mg per dose) OR cefadroxil 30 mg/kg once daily (maximum 1 gram) for 10 days 5, 2
• These have strong, high-quality evidence and are safe in patients without immediate hypersensitivity reactions 5

Immediate/Anaphylactic Allergy (avoid all beta-lactams):

• Clindamycin (preferred): 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 5, 2
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 5, 6
• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 5
• Erythromycin: 20-40 mg/kg/day divided 2-3 times daily for 10 days (less preferred due to gastrointestinal side effects) 3, 7

Critical Treatment Principles

Duration Requirements:

• All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication and prevent acute rheumatic fever, even if symptoms resolve earlier 5, 1, 2
• Azithromycin requires only 5 days due to its prolonged tissue half-life 5, 6
• Therapy can be safely postponed up to 9 days after symptom onset and still prevent rheumatic fever 5

Contagiousness:

• Patients are no longer contagious after 24 hours of appropriate antibiotic therapy, but must complete the full course 1

Important Considerations and Pitfalls

Macrolide Resistance:

• Macrolide resistance among Group A Streptococcus ranges from 5-8% in the United States but varies geographically 5
• Be aware of local resistance patterns before prescribing azithromycin or clarithromycin 5, 2
• Clindamycin resistance is approximately 1% in the United States 5

Cephalosporin Cross-Reactivity:

• Up to 10% of patients with immediate penicillin hypersensitivity may have cross-reactivity with first-generation cephalosporins 3, 5
• Never use cephalosporins in patients with immediate/anaphylactic penicillin reactions 5

Common Prescribing Errors to Avoid:

• Do not prescribe shorter courses than recommended (except azithromycin's 5-day regimen) as this leads to treatment failure and complications 5
• Do not assume all penicillin-allergic patients cannot receive cephalosporins—only those with immediate/anaphylactic reactions should avoid them 5
• Do not use trimethoprim-sulfamethoxazole for strep throat due to high resistance rates (50%) 5

Adjunctive Therapy

Symptomatic Relief:

• Acetaminophen or NSAIDs (ibuprofen) for moderate to severe symptoms or high fever 5
• Avoid aspirin in children due to risk of Reye syndrome 5
• Do not use corticosteroids as adjunctive therapy 5

Special Situations

When to Use Intramuscular Penicillin:

• Patients unlikely to complete a full 10-day oral course 3
• Areas where rheumatic fever is prevalent, particularly in populations with episodic medical care and poor follow-up 8
• Documented outbreaks in schools, day care centers, or institutions 3

Household Contacts:

• It is not necessary to perform throat cultures or treat asymptomatic household contacts except in situations with increased risk of frequent infections or non-suppurative sequelae 3

Post-Treatment Testing:

• Routine follow-up throat cultures are not recommended for asymptomatic patients who have completed therapy 5
• Consider testing only in special circumstances, such as patients with a history of rheumatic fever 5