From the Guidelines
The recommended oral dosing for metronidazole is 500 mg twice a day for 7 days, as indicated for bacterial vaginosis. This dosing is supported by the Centers for Disease Control and Prevention guidelines 1. For other conditions, the dosing may vary:
- For bacterial infections like anaerobic infections, the standard dose is 500 mg every 8 hours for 7-10 days.
- For protozoal infections, dosing varies:
- Amoebiasis requires 500-750 mg three times daily for 5-10 days.
- Giardiasis can be treated with 250 mg three times daily for 5-7 days or a single 2-gram dose.
- For trichomoniasis, metronidazole can be given as a single 2-gram dose or 500 mg twice daily for 7 days, as per guidelines from the Journal of Microbiology, Immunology and Infection 1. Metronidazole works by disrupting bacterial DNA, making it effective against anaerobic organisms. The medication should be taken with food to minimize gastrointestinal side effects, and patients should avoid alcohol during treatment and for 48 hours afterward to prevent disulfiram-like reactions. Dose adjustments may be necessary for patients with severe hepatic impairment.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION ... Trichomoniasis ... One-day treatment— two grams of metronidazole tablets, given either as a single dose or in two divided doses of one gram each given in the same day ... Seven-day course of treatment— 250 mg three times daily for seven consecutive days. Adults For acute intestinal amebiasis (acute amebic dysentery): 750 mg orally three times daily for 5 to 10 days. The usual adult oral dosage is 7. 5 mg/kg every six hours (approx. 500 mg for a 70 kg adult).
The recommended oral (PO) dosing for metronidazole varies depending on the condition being treated:
- Trichomoniasis:
- One-day treatment: 2 grams, given as a single dose or in two divided doses
- Seven-day course: 250 mg three times daily
- Amebiasis:
- Acute intestinal amebiasis: 750 mg orally three times daily for 5 to 10 days
- Anaerobic Bacterial Infections: 7.5 mg/kg every six hours (approximately 500 mg for a 70 kg adult) 2
From the Research
Metronidazole PO Dosing
- The recommended oral (PO) dosing for metronidazole varies depending on the condition being treated 3, 4, 5.
- For the treatment of Trichomonas vaginalis infections, a single 2-g oral dose of metronidazole is highly effective 3, 4.
- Mildly resistant infections can usually be cured with metronidazole oral doses of 2 g daily for 3-7 days 3.
- For the treatment of bacterial vaginosis, metronidazole (500 mg twice daily for 7 days) is highly efficacious 3.
- A 7-day dose of metronidazole (500 mg twice daily) has been shown to be more effective than a single 2-g dose for the treatment of trichomoniasis in women 5.
- The 7-day dose regimen has been recommended as the preferred treatment for trichomoniasis among women due to its higher efficacy and similar side-effect profile compared to the single-dose regimen 5.
Specific Dosing Regimens
- Single 2-g oral dose: effective for Trichomonas vaginalis infections 3, 4
- 2 g daily for 3-7 days: effective for mildly resistant Trichomonas vaginalis infections 3
- 500 mg twice daily for 7 days: effective for bacterial vaginosis 3
- 500 mg twice daily for 7 days: preferred treatment for trichomoniasis in women 5