Table Recommended Prophylaxis Against Recurrent Group A Streptococcal Infection Regimen Drug Dosage Standard Penicillin G benzathine 1.2 million units IM every 3 - 4 weeks * ≤ 27 kg: 600, 000 units IM every 3 - 4 weeks * Alternatives (eg, for patients unwilling to receive injections) Penicillin V or Sulfadiazine or Sulfisoxazole 250 mg orally 2 times a day ≤ 27 kg: 500 mg orally once a day > 27 kg: 1 g orally once a day For patients allergic to penicillin and sulfa drugs Erythromycin or Azithromycin 250 mg orally 2 times a day 250 mg orally once a day * In parts of the world with high acute rheumatic fever endemicity, IM prophylaxis every 3 weeks is superior to every 4 weeks.