What is the recommended dose of penicillin (Penicillin V) for a child weighing 110 pounds with streptococcal pharyngitis?

Penicillin V Dosing for a 110-Pound Child with Streptococcal Pharyngitis

For a child weighing 110 pounds (50 kg), give penicillin V 500 mg twice daily for 10 days. 1

Weight-Based Dosing Calculation

• A 110-pound child weighs 50 kg, which exceeds the 27 kg threshold where adult dosing applies 1
• For adolescents and adults (≥27 kg), the recommended dose is 500 mg twice daily for 10 days 1
• Alternative dosing of 250 mg four times daily is also acceptable but less convenient for adherence 1

Critical Treatment Principles

• Complete the full 10-day course even when symptoms resolve early—this is essential to prevent acute rheumatic fever 1, 2
• The child becomes non-contagious after 24 hours of antibiotic therapy 1, 3
• Penicillin remains the drug of choice due to its narrow spectrum, proven efficacy, safety profile, and low cost 1
• No penicillin-resistant Group A Streptococcus has ever been documented 1

Alternative Regimens if Needed

If considering amoxicillin instead (which has better palatability and once-daily dosing):

• Give 1000 mg once daily for 10 days 1, 2, 3
• Or 500 mg twice daily for 10 days 1, 2

For penicillin allergy:

• Cephalexin 500 mg twice daily for 10 days (avoid if immediate-type hypersensitivity) 1
• Clindamycin 300 mg three times daily for 10 days 1
• Azithromycin 500 mg once daily for 5 days (note: macrolide resistance varies geographically) 1

Common Pitfalls to Avoid

• Do not use once-daily penicillin V dosing—studies show higher failure rates with 1000 mg once daily compared to divided dosing 4
• Twice-daily dosing (500 mg) is superior to once-daily dosing and comparable to four-times-daily regimens 4
• Do not stop treatment early when symptoms improve—this increases risk of rheumatic fever and treatment failure 1