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Below are the general guidelines for dosing metronidazole. Note that these dosages may be adjusted on a case-by-case basis for individual patients by a provider. Always follow your prescribing physician’s instructions for taking metronidazole.

The following information comes from DailyMed, the official FDA label information provider for drugs.

What if I miss a dose of Metronidazole?

If you miss a dose of metronidazole, take it as soon as you can. If it’s almost time for your next dose, however, skip the missed dose and revert back to your regular schedule. Be sure not to double your doses.

What if I overdose on Metronidazole?

Single oral doses of metronidazole, up to 15 g, have been reported in suicide attempts and accidental overdoses. Symptoms reported include nausea, vomiting, and ataxia.

Oral metronidazole has been studied as a radiation sensitizer in the treatment of malignant tumors. Neurotoxic effects, including seizures and peripheral neuropathy, have been reported after 5 to 7 days of doses of 6 to 10.4 g every other day.

If you believe you have overdosed on metronidazole call poison control 1-(800)-222-1222.


There is no specific antidote for metronidazole overdose; therefore, the management of the patient should consist of symptomatic and supportive therapy.

How is Metronidazole administered?

In elderly patients, the pharmacokinetics of metronidazole may be altered, and, therefore, monitoring of serum levels may be necessary to adjust the metronidazole dosage accordingly.


In the Female

One-day treatment— two grams of metronidazole, 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. There is some indication from controlled comparative studies that cure rates as determined by vaginal smears, signs and symptoms, may be higher after a seven-day course of treatment than after a one-day treatment regimen.

The dosage regimen should be individualized. Single-dose treatment can assure compliance, especially if administered under supervision, in those patients who cannot be relied on to continue the seven-day regimen. A seven-day course of treatment may minimize reinfection by protecting the patient long enough for the sexual contacts to obtain appropriate treatment. Further, some patients may tolerate one treatment regimen better than the other.

Pregnant patients should not be treated during the first trimester. Pregnant patients in whom alternative treatment has been inadequate, the one-day course of therapy should not be used, as it results in higher serum levels which can reach the fetal circulation.

When repeat courses of the drug are required, it is recommended that an interval of four to six weeks elapse between courses and that the presence of the trichomonad be reconfirmed by appropriate laboratory measures. Total and differential leukocyte counts should be made before and after retreatment.

In the Male

Treatment should beindividualized as for the female.



For acute intestinal amebiasis (acute amebic dysentery): 750 mg orally three times daily for 5 to 10 days.

For amebic liver abscess: 500 mg or 750 mg orally three times daily for 5 to 10 days.

Pediatric patients

35 to 50 mg/kg/24 hours, divided into three doses, orally for 10 days.

Anaerobic Bacterial Infections

In the treatment of most serious anaerobic infections, the intravenous form of metronidazole is usually administered initially.

The usual adult oral dosage is 7.5 mg/kg every six hours (approx. 500 mg for a 70-kg adult). A maximum of 4 g should not be exceeded during a 24-hour period.

The usual duration of therapy is 7 to 10 days; however, infections of the bone and joint, lower respiratory tract, and endocardium may require longer treatment.

Patients with severe hepatic disease metabolize metronidazole slowly, with resultant accumulation of metronidazole and its metabolites in the plasma. Accordingly, for such patients, doses below those usually recommended should be administered cautiously. Close monitoring of plasma metronidazole levels2 and toxicity is recommended.

The dose of metronidazole should not be specifically reduced in anuric patients since accumulated metabolites may be rapidly removed by dialysis.

How is Metronidazole supplied?

Metronidazole Tablets USP 250 mg are 11/32״, unscored, round, white to off-white tablets imprinted DAN and 5540 supplied in bottles of 50, 100, 250, 500 and 1000.

Metronidazole Tablets USP 500 mg are 17/32״, scored, round, white to off-white tablets imprinted DAN and 5552 supplied in bottles of 50, 100, 250, 500, and 1000. Dispense in a well-closed, light-resistant container with a child-resistant closure.

Store below 86°F (30°C).

Protect from light.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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