Metronidazole Capsules or Tablets

Metronidazole is a medication that treats infections caused by bacteria or parasites. The brand name of this medication is Flagyl®. You can take this tablet or capsule by mouth with a glass of water.

What is this medication?

METRONIDAZOLE (me troe NI da zole) treats infections caused by bacteria or parasites. It belongs to a group of medications called antibiotics. It will not treat colds, the flu, or infections caused by viruses.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Flagyl

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What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

  • Cockayne syndrome
  • History of blood diseases such as sickle cell anemia, anemia, or leukemia
  • If you often drink alcohol
  • Irregular heartbeat or rhythm
  • Kidney disease
  • Liver disease
  • Yeast or fungal infection
  • An unusual or allergic reaction to metronidazole, nitroimidazoles, or other medications, foods, dyes, or preservatives
  • Pregnant or trying to get pregnant
  • Breast-feeding

How should I use this medication?

Take this medication by mouth with water. Take it as directed on the prescription label at the same time every day. Take all of this medication unless your care team tells you to stop it early. Keep taking it even if you think you are better.

Talk to your care team about the use of this medication in children. While it may be prescribed for children for selected conditions, precautions do apply.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

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What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medication?

Do not take this medication with any of the following:

  • Alcohol or any product that contains alcohol
  • Cisapride
  • Disulfiram
  • Dronedarone
  • Pimozide
  • Thioridazine

This medication may also interact with the following:

  • Birth control pills
  • Busulfan
  • Carbamazepine
  • Certain medications that treat or prevent blood clots like warfarin
  • Cimetidine
  • Lithium
  • Other medications that prolong the QT interval (cause an abnormal heart rhythm)
  • Phenobarbital
  • Phenytoin

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

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What should I watch for while using this medication?

Tell your care team if your symptoms do not start to get better or if they get worse.

Some products may contain alcohol. Ask your care team if this medication contains alcohol. Be sure to tell all care teams you are taking this medication. Certain medications, such as metronidazole and disulfiram, can cause an unpleasant reaction when taken with alcohol. The reaction includes flushing, headache, nausea, vomiting, sweating, and increased thirst. The reaction can last from 30 minutes to several hours.

If you are being treated for a sexually transmitted disease (STD), avoid sexual contact until you have finished your treatment. Your sexual partner may also need treatment.

Birth control may not work properly while you are taking this medication. Talk to your care team about using an extra method of birth control.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Dizziness, loss of balance or coordination, confusion or trouble speaking
  • Fever, neck pain or stiffness, sensitivity to light, headache, nausea, vomiting, confusion
  • Heart rhythm changes—fast or irregular heartbeat, dizziness, feeling faint or lightheaded, chest pain, trouble breathing
  • Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
  • Pain, tingling, or numbness in the hands or feet
  • Redness, blistering, peeling, or loosening of the skin, including inside the mouth
  • Seizures
  • Severe diarrhea, fever
  • Sudden eye pain or change in vision such as blurry vision, seeing halos around lights, vision loss
  • Unusual vaginal discharge, itching, or odor

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

  • Diarrhea
  • Metallic taste in mouth
  • Nausea
  • Stomach pain

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children and pets.

Store between 15 and 25 degrees C (59 and 77 degrees F). Protect from light. Get rid of any unused medication after the expiration date.

To get rid of medications that are no longer needed or have expired:

  • Take the medication to a medication take-back program. Check with your pharmacy or law enforcement to find a location.
  • If you cannot return the medication, check the label or package insert to see if the medication should be thrown out in the garbage or flushed down the toilet. If you are not sure, ask your care team. If it is safe to put it in the trash, take the medication out of the container. Mix the medication with cat litter, dirt, coffee grounds, or other unwanted substance. Seal the mixture in a bag or container. Put it in the trash.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

Copyright ©2024 Elsevier Inc. All Rights Reserved.

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Note: Introduction and Additional Common Questions written and medically approved by Cleveland Clinic professionals.

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