metronidazole



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Flagyl, Flagyl 375, Flagyl ER

What is metronidazole?

Metronidazole is an antibiotic. It fights bacteria in your body.

Metronidazole is used to treat bacterial infections of the vagina, stomach, skin, joints, and respiratory tract. This medication will not treat a vaginal yeast infection.

Metronidazole may also be used for other purposes not listed in this medication guide.

What is the most important information I should know about metronidazole?

Take this medication for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated. Metronidazole will not treat a viral infection such as the common cold or flu.

Do not drink alcohol while you are taking metronidazole and for at least 3 days after you stop taking it. You may have unpleasant side effects such as fast heartbeats, warmth or redness under your skin, tingly feeling, nausea, and vomiting.

What should I discuss with my healthcare provider before taking metronidazole?

Do not use this medication if you are allergic to metronidazole, or if you are in the first trimester of pregnancy. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

Before taking metronidazole, tell your doctor if you are allergic to any drugs, or if you have:

  • liver disease
  • a stomach or intestinal disease such as Crohn's disease
  • a blood cell disorder such as anemia (lack of red blood cells) or leukopenia (lack of white blood cells)
  • epilepsy or other seizure disorder; or
  • nerve disorders.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take this medication.

Metronidazole can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take metronidazole?

Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.

Take the extended-release form of metronidazole (Flagyl ER) on an empty stomach, at least 1 hour before or 2 hours after eating a meal.

Do not crush, chew, or break the extended-release tablet. Swallow the pill whole. It is specially made to release medicine slowly in the body. Breaking the pill would cause too much of the drug to be released at one time.

Take this medication for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated. Metronidazole will not treat a viral infection such as the common cold or flu.

To be sure this medication is not causing harmful effects, your blood will need to be tested on a regular basis. Your liver function may also need to be tested. Do not miss any scheduled visits to your doctor.

This medication can cause you to have unusual results with certain medical tests. Tell any doctor who treats you that you are using metronidazole.

Store metronidazole at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at your next regularly scheduled time. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include nausea, vomiting, dizziness, loss of balance or coordination, numbness and tingling, or seizures (convulsions).

What should I avoid while taking metronidazole?

Do not drink alcohol while you are taking metronidazole and for at least 3 days after you stop taking it. You may have unpleasant side effects such as fast heartbeats, warmth or redness under your skin, tingly feeling, nausea, and vomiting.

Check the labels of any medicines or food products you use to make sure they do not contain alcohol.

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or has blood in it, call your doctor. Do not use any medicine to stop the diarrhea unless your doctor has told you to.

What are the possible side effects of metronidazole?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • seizures (convulsions)
  • fever, chills, body aches, sore throat, flu symptoms
  • numbness or tingling in your hands or feet
  • white patches or sores inside your mouth or on your lips
  • pain or burning when you urinate; or
  • diarrhea that is watery or bloody.

Less serious side effects may include:

  • nausea, stomach pain, diarrhea
  • headache, dizziness, loss of balance
  • vaginal itching or discharge
  • dry mouth or unpleasant metallic taste
  • cough, sneezing, runny or stuffy nose; or
  • swollen or sore tongue.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect metronidazole?

Before taking this medication, tell your doctor if you are taking any of the following medicines:

  • cimetidine (Tagamet)
  • seizure medication such as phenytoin (Dilantin) or phenobarbital (Luminal, Solfoton)
  • a blood thinner such as warfarin (Coumadin)
  • lithium (Lithobid, Eskalith, others); or
  • disulfiram (Antabuse).

This list is not a complete and there may be other drugs that can interact with metronidazole. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Where can I get more information?

Your pharmacist can provide more information about metronidazole.


Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.