Metronidazole (Flagyl) GYN

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Metronidazole (Met roh NID ah zole) is the generic name for (Flagyl (FLAH jel®)). Other brand names for this medicine are MetroGel®, MetroGel-Vaginal®, and Flagyl ER®

This medicine is an antibiotic that treats certain infections by killing bacteria. It may be used to treat vaginal infections. A germ called trichomonas (trick uh MOE nus) causes these infections. Trichomoniasis (trick uh moe NIH uh sis) is a sexually transmitted infection (STI). Some other vaginal infections you do not get through sex are also treated with metronidazole. Male sex partner(s) should be treated at the same time. A male can carry the germs that cause these diseases but he may not have any symptoms. Even though he has no symptoms, he can still pass on the infection until he is treated. Symptoms usually go away in 2 to 3 days.

How to take this medicine

  • Read the label carefully. Make sure you are taking the right dose. It is easy to confuse the many different dosage forms and strengths.
  • Take the exact dose of medicine that your doctor ordered.
  • Ask the pharmacist, nurse, or doctor before crushing any medicine.
  • This medicine should be taken 1 hour before or 2 hours after eating. If your stomach gets upset, the medicine can be taken with food.
  • It is very important to finish all the medicine that is ordered for _____ days. Do not stop the medicine early, even if you are feeling better.

If you forget to take a dose

Read the label

If you forget to take a dose of this medicine, take it as soon as possible. If it is almost time for the next dose, do not take the missed dose at all. Do not double the next dose. Instead, go back to your regular dosing schedule. If you have any questions about this, check with your doctor or pharmacist.

If a dose is vomited

  • If you gag or choke and spit out the dose before swallowing it, relax for a minute and then take the same amount one more time.
  • Even if the medicine is thrown up (vomited) right after taking it, do not repeat the dose. Some of the medicine may still be in the stomach. Do not repeat the dose unless it is in tablet form and you can see that the whole tablet was vomited. The vomiting might be due to the strong taste of the medicine.
  • If vomiting happens again with future doses, call your doctor.

Medicine storage

  • Store all medicine out of the reach of children.
  • Always keep medicine in the original bottle from the pharmacy.
  • Do not keep this medicine in the refrigerator. Store it at room temperature.
  • Light and moisture make this medicine not work as well. Keep the bottle tightly closed. Store it in a dark, dry place. Do not keep it in the bathroom or above the kitchen sink.
  • Keep this medicine away from heat or direct sunlight.
  • Do not use this medicine after the expiration dateprinted on the container.
  • When the medicine is no longer needed, mix the leftover medicine with material you are going to throw away, like coffee grounds. Put the mixture into a container or a bag that will not leak. Throw the container in the trash where children and pets cannot reach it.

Drug – nutrient interactions

  • You should not drink alcohol. Mixing this medicine with alcohol can cause severe nausea, vomiting, cramps, headache, flushing (redness of the face) and can be dangerous. Some cold medicines, cough syrups, and mouthwashes have alcohol.
  • Check with the doctor or pharmacist before taking over-the-counter medicines. Do not drink alcohol for another 2 days after you have finished taking metronidazole.
  • This medicine should not be taken with these products or medicines: alcohol, rifampin, phenobarbital, phenytoin (Dilantin®), lithium, and warfarin (Coumadin®).


If you are allergic to metronidazole, you should not take this medicine.

Special note for female patients

  • If you think you might be pregnant, you should tell the doctor before you begin taking this or any medicine. This medicine may cause problems if taken during pregnancy.
  • If a patient is breast-feeding, she should tell her doctor before she begins taking this or any medicine. This medicine can pass into breast milk and cause side effects in the baby.

Possible side effects

  • Taste of “metal” in the mouth
  • Nausea, loss of appetite, dry mouth
  • Brown-colored urine
  • Diarrhea
  • Rash
  • Vomiting (not common)
  • Numbness or tingling of fingers or toes

Metronidazole (Flagyl) - GYN (PDF)

HH-V-31 6/99 Revised 07/16 Copyright 1999, Nationwide Children’s Hospital