Intestinal & hepatic amoebiasis Adult 750 mg 3 times daily for 5-10 days. 
Childn 35-50 mg/kg/day in 3 divided doses for 10 days. 
Trichomoniasis For re-infection prophylaxis, patient's spouse should be given the same dose 
Adult 2 g in single dose for 1 day or 500 mg twice daily or 250 mg 3 times daily for 7 consecutive days. 
Childn 15 mg/kg/day in 3 divided doses for 7-10 days. 
Giardiasis Adult 250 mg-500 mg 3 times daily for 5-7 days or 2 g daily in single dose for 3 days. 
Childn 5 mg/kg 3 times daily for 5-7 days. 
Anaerob bacterial infection For serious infections, metronidazole IV should be administered at the start of treatment. 
Adult 7.5 mg/kg 6 hrly. 
Adult w/ 70 kg body wt ±500 mg. Max dose: 4 g daily for 7-10 days.