Choices include Penicillin V 500 mg (250 mg for children < 27 kg) orally every 12 hours Amoxicillin 50 mg / kg (maximum 1 g) once a day for 10 days (which is an effective substitute for penicillin V) Oral narrow-spectrum cephalosporins (eg, cephalexin, cefadroxil) are also effective and can be used unless patients have an anaphylactic reaction to penicillin.