Acute uncomplicated cystitis
Adult: 200 mg bid for 7 days or 200 mg tid for 5 days. Alternatively, an initial dose of 400 mg followed by 200 mg tid for 8 doses may be used.
Oral
Chronic or recurrent bacteriuria
Adult: 400 mg 3-4 times daily.
Child: >40 kg: Same as adult dose.
Child: >40 kg: Same as adult dose.
Oral
Urinary tract infection
Child: <40 kg: 20-40 mg/kg daily in 3-4 divided doses.