Generic name: Metronidazole.

Other brand names: 

Femazole, Metizol, MetroGel, Metryl, Protostat, Satric.

Flagyl is an amoebicide/antibiotic. It acts by killing bacteria or parasites. 

Quick Facts About Flagyl


Used to treat vaginal and urinary tract infections in men and women; amoebic dysentery and liver abscesses; infections of the abdomen, skin, bones, joints, brain, lungs, and heart caused by bacteria.

Flagyl Dosage

Take medication consistently and on schedule. Works best when the body maintains a constant level of the medication. If treated for trichomoniasis (sexually transmitted infection), your doctor may also treat your partner, even if there are no symptoms. Avoid sexual intercourse during treatment until cured, or use a condom. Can take with or without food.

  • Usual adult dose: for trichomoniasis — 1 day treatment — 2 grams in a single dose or divided into 2 doses; 7 day treatment — 250 milligrams taken 3 times
    per day for 7 consecutive days. For acute amoebic dysentery — 750 milligrams taken orally 3 times per day for 5 to 10 days. For amoebic liver abscess — 500 milligrams or 750 milligrams taken orally 3 times per day for 5 to 10 days. For anaerobic bacterial infections — 7.5 milligrams per 2.2 pounds of body weight taken orally every 6 hours. Seniors — doctor may adjust dosage.
  • Usual child dose: 35 to 50 milligrams per 2.2 pounds of body weight per day, divided into 3 doses, taken for 10 days.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Flagyl Side Effects

Overdose symptoms:

lack of muscle coordination, nausea, vomiting. If you suspect an overdose, immediately seek medical attention.

More common side effects: abdominal cramps, constipation, diarrhea, headache, loss of appetite, nausea, upset stomach, vomiting.

Less common Flagyl side effects: blood disorders, confusion, dark urine, decreased sex drive, depression, difficulty sleeping, dizziness, dry mouth, dry vagina or vulva, fever, flushing, furry tongue, hives, inability to hold urine, increased production of pale urine, inflamed mouth or tongue, inflammation of the rectum, irritability, lack of muscle coordination, metallic taste, occasional joint pain, pain during sexual intercourse, painful or difficult urination, pelvic pressure, rash, stuffy nose, vaginal yeast infection, vertigo, weakness. If you experience seizures and numbness or tingling in the arms, legs, hands, and feet, stop taking the medication and immediately contact your doctor.


Inform your doctor before combining Flagyl with:

blood thinners such as Coumadin; cholestyramine (Questran); cimetidine (Tagamet); disulfiram (Antabuse); lithium (Lithonate); phenobarbital; phenytoin (Dilantin).

Do not drink alcohol during Flagyl therapy and for 24 hours after final dose. Also avoid medications containing alcohol such as cough and cold syrups. 

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Appears in breast milk; could affect a nursing infant. Should not use during first trimester of pregnancy.

Doctor may adjust dosage for seniors.

Follow doctor’s instructions carefully for children.

  • Do not take if sensitive to or allergic to Flagyl or similar medications.
  • Inform your doctor if you have liver disease.
  • Yeast infections may appear or worsen during Flagyl therapy.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Flagyl side effects, please contact your healthcare provider.