Metronidazole

Antibacterial

For more detailed drug information, see Metronidazole in the AMH.

Dosage – Metronidazole

Length of course depends on the infection and its response to treatment.

Anaerobic bacterial infections

Birth (at term) – 1 month

Doses used locally may differ from those below.

Oral, 7.5 mg/kg every 12 hours.

IV, initially 15 mg/kg, then 7.5 mg/kg every 12 hours.

1 month – 18 years

Oral, 7.5 mg/kg (maximum 400 mg) 3 times a day or 10 mg/kg (maximum 400 mg) twice daily. Usual adult dose 200–400 mg every 8–12 hours.

IV, 7.5 mg/kg (maximum 500 mg) 3 times a day or 12.5 mg/kg (maximum 500 mg) twice daily (3 times a day for clostridial or CNS infections). Usual adult dose 500 mg every 8–12 hours.

Rectal

1–12 months, rectal 125 mg 3 times a day for 3 days, then twice daily.

1–5 years, rectal 250 mg 3 times a day for 3 days, then twice daily.

5–12 years, rectal 500 mg 3 times a day for 3 days, then twice daily.

12–18 years, rectal 1 g 3 times a day for 3 days, then twice daily.

Giardiasis

1 month – 18 years, oral 30 mg/kg once daily (maximum 2 g) for 3 days or 10 mg/kg (maximum 400 mg) 3 times a day for 5–7 days.

Trichomoniasis

Post-puberty, oral 2 g as a single dose; if this fails, 400 mg twice daily for 7 days.

Helicobacter pylori eradication

Seek paediatric gastroenterologist advice.

1 month – 18 years, oral 10 mg/kg (maximum 400 mg) twice daily (with a PPI and another antibacterial).

Clostridioides difficile-associated disease

Treat for 10 days.

First episode, mild disease

1 month – 18 years, oral 10 mg/kg (maximum 400 mg) 3 times a day.

Severe disease

1 month – 18 years, IV 12.5 mg/kg (maximum 500 mg) 3 times a day with vancomycin.

Amoebiasis due to Entamoeba histolytica

Follow course with paromomycin.

Acute intestinal amoebiasis, treat for 7–10 days.

Extra-intestinal amoebiasis, including liver abscess, treat for 14 days; seek specialist advice.

1 month – 18 years, oral 15 mg/kg (maximum 800 mg) every 8 hours. Usual adult dose 600–800 mg every 8 hours.

Surgical prophylaxis

1 month – 18 years, IV 12.5 mg/kg (maximum 500 mg) within 2 hours before incision.

Administration advice

Tablets: take with food.

Oral liquid: take 1 hour before food.

For information about parenteral administration, see the Royal Children's Hospital Paediatric Injectable Guidelines.

Off-label use

Product information does not include doses for eradication of H. pylori.

Practice points

• reduce dose in severe hepatic impairment

• second line for H. pylori and C. difficile infections

• twice-daily dosing for anaerobic infections is recommended by respected Australian sources, however, there are few published data to support this

• despite widespread use, there is little published evidence to support neonatal dosing

Products

Search for Metronidazole on the PBS

• tab, 200 mg, 21, Metronidamed, PBS

• tab, 200 mg (scored), 21, Metrogyl, PBS

• tab, 400 mg, 21, Metronidamed, PBS‑R¹

• tab, 400 mg (scored), 21, Flagyl, Metrogyl, PBS‑R¹

• oral liquid, 40 mg/mL, 100 mL, Flagyl S, PBS

• supp, 500 mg, 10, Flagyl, PBS

• inj, 5 mg/mL, 100 mL, 5, 10, Metronidazole^a

• cream, 0.75%, 30 g, Rozex

• gel, 0.75%, 50 g, Rozex

¹ anaerobic infections

^a generic brands available