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Drugs reference index «Flagyl»



Generic name: MetronidazoleBrand names: Flagyl

Why is Flagyl prescribed?

Flagyl is an antibacterial drug prescribed for certain vaginal and urinary tract infections in men and women; amebic dysentery and liver abscess; and infections of the abdomen, skin, bones and joints, brain, lungs, and heart caused by certain bacteria.

Most important fact about Flagyl

Do not drink alcoholic beverages while taking Flagyl. The combination can cause abdominal cramps, nausea, vomiting, headaches, and flushing. It can also change the taste of the alcoholic beverage. When you have stopped taking Flagyl, wait at least 72 hours (3 days) before consuming any alcohol. Also avoid over-the-counter medications containing alcohol, such as certain cough and cold products.

How should you take Flagyl?

Flagyl works best when there is a constant amount in the blood. Take your doses at evenly spaced intervals, day and night, and try to avoid missing any.

If you are being treated for the sexually transmitted genital infection called trichomoniasis, your doctor may want to treat your partner at the same time, even if there are no symptoms. Try to avoid sexual intercourse until the infection is cured. If you do have sex, use a condom.

Flagyl can be taken with or without food. It may cause dry mouth. Hard candy, chewing gum, or bits of ice can help to relieve the problem.

  • If you miss a dose...Take it as soon as you remember. If it is almost time for your next dose skip the one you missed and go back to your regular schedule. Do not take 2 doses at once.
  • Storage instructions...Store at room temperature. Protect from light.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor immediately. Only your doctor can determine whether it is safe for you to continue taking Flagyl.

Two serious side effects that have occurred with Flagyl are seizures and numbness or tingling in the arms, legs, hands, and feet. If you experience either of these symptoms, stop taking the medication and call your doctor immediately.

  • Side effects may include:Abdominal cramps, constipation, diarrhea, headache, loss of appetite, nausea, upset stomach, vomiting

Why should Flagyl not be prescribed?

Flagyl should not be used during the first 3 months of pregnancy to treat vaginal infections. Do not take Flagyl if you have ever had an allergic reaction to or are sensitive to metronidazole or similar drugs. Tell your doctor about any drug reactions you have experienced.

Special warnings about Flagyl

If you experience seizures or numbness or tingling in your arms, legs, hands, or feet, remember that you should stop taking Flagyl and call your doctor immediately.

If you have liver disease, make sure the doctor is aware of it. Flagyl should be used with caution.

Active or undiagnosed yeast infections may appear or worsen when you take Flagyl.

Possible food and drug interactions when taking Flagyl

Do not drink alcohol while taking Flagyl and for at least 72 hours after your last dose.

If Flagyl is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Flagyl with any of the following:

Blood thinners such as warfarinCholestyramineCimetidineDisulfiramLithiumPhenobarbitalPhenytoin

Special information if you are pregnant or breastfeeding

The effects of Flagyl in pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, notify your doctor. This medication should be used during pregnancy only if it is clearly needed. Flagyl appears in breast milk and could affect a nursing infant. If Flagyl is essential to your health, your doctor may advise you to stop breastfeeding until your treatment is finished.

Recommended dosage for Flagyl



One-day treatment: 2 grams of Flagyl, taken as a single dose or divided into 2 doses (1 gram each) taken in the same day.

Seven-day course of treatment: 250 milligrams 3 times daily for 7 consecutive days.

Acute Intestinal Amebiasis (Acute Amebic Dysentery)

The usual dose is 750 milligrams taken by mouth 3 times daily for 5 to 10 days.

Amebic Liver Abscess

The usual dose is 500 milligrams or 750 milligrams taken by mouth 3 times daily for 5 to 10 days.

Anaerobic Bacterial Infections

The usual adult oral dosage is 7.5 milligrams per 2.2 pounds of body weight every 6 hours.



The usual dose is 35 to 50 milligrams for each 2.2 pounds of body weight per day, divided into 3 doses taken for 10 days.

The safety and efficacy of Flagyl for any other condition in children have not been established.


Your doctor will test to see how much medication is in your blood and will adjust your dosage if necessary.


Any medication taken in excess can have serious consequences. If you suspect an overdose, seek medical treatment immediately.

  • Symptoms of Flagyl overdose may include:Lack of muscle coordination, nausea, vomiting
  • Flagyl Consumer Overview
  • Flagyl Oral, Intravenous Advanced Consumer (Micromedex) - Includes Dosage Information
  • Flagyl MedFacts Consumer Leaflet (Wolters Kluwer)
  • Metronidazole Prescribing Information (FDA)
  • Metronidazole Professional Patient Advice (Wolters Kluwer)
  • Metronidazole MedFacts Consumer Leaflet (Wolters Kluwer)
  • Flagyl Prescribing Information (FDA)
  • Flagyl ER Extended-Release Tablets MedFacts Consumer Leaflet (Wolters Kluwer)
  • Flagyl ER Prescribing Information (FDA)

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