Generic Name: metronidazole (me troe NI da zole)
Brand Name: Flagyl, Flagyl 375, Flagyl ER
What is Flagyl ER (metronidazole)?
Metronidazole is an antibiotic that fights bacteria.
Metronidazole is used to treat bacterial infections of the vagina, stomach, liver, skin, joints, brain, and respiratory tract. This medication will not treat a vaginal yeast infection.
Metronidazole may also be used for purposes not listed in this medication guide.
What is the most important information I should know about Flagyl ER (metronidazole)?
You should not use metronidazole if you are allergic to it, or if you have taken disulfiram (Antabuse) within the past 2 weeks.
Do not drink alcohol or consume foods or medicines that contain propylene glycol while you are taking metronidazole and for at least 3 days after you stop taking it.
In animal studies, metronidazole caused certain types of cancers or tumors. It is not known whether these effects would occur in people using this medicine. Ask your doctor about your risk.
What should I discuss with my healthcare provider before taking Flagyl ER (metronidazole)?
You should not take metronidazole if you are allergic to it, or if you have taken disulfiram (Antabuse) within the past 2 weeks.
To make sure metronidazole is safe for you, tell your doctor if you have ever had:
a stomach or intestinal disease such as Crohn's disease;
a blood cell disorder such as anemia (lack of red blood cells) or low white blood cell (WBC) counts;
a fungal infection anywhere in your body; or
a nerve disorder.
In animal studies, metronidazole caused certain types of tumors, some of which were cancerous. However, very high doses are used in animal studies. It is not known whether these effects would occur in people using regular doses. Ask your doctor about your risk.
Using metronidazole during pregnancy could harm the unborn baby. Tell your doctor if you are pregnant or if you become pregnant while using this medicine.
Metronidazole can pass into breast milk and may harm a nursing baby. You should not breast-feed within 24 hours after using metronidazole. If you use a breast pump during this time, throw out any milk you collect. Do not feed it to your baby.
Do not give this medicine to a child without medical advice.
How should I take Flagyl ER (metronidazole)?
Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
Do not crush, chew, or break an extended-release tablet. Swallow it whole.
If are treating a vaginal infection, your sexual partner may also need to take metronidazole (even if no symptoms are present) or you could become reinfected.
Metronidazole is usually given for up to 10 days in a row. You may need to repeat this dosage several weeks later.
Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Metronidazole will not treat a viral infection such as the flu or a common cold.
Metronidazole can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using this medicine.
Store at room temperature away from moisture and heat.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include nausea, vomiting, dizziness, loss of balance or coordination, numbness and tingling, or seizures (convulsions).
What should I avoid while taking Flagyl ER (metronidazole)?
Do not drink alcohol or consume food or medicines that contain propylene glycol while you are taking metronidazole. You may have unpleasant side effects such as headaches, stomach cramps, nausea, vomiting, and flushing (warmth, redness, or tingly feeling). Also avoid alcohol or propylene glycol for at least 3 days after you stop taking metronidazole.
Check the labels of any medicines or food products you use to make sure they do not contain alcohol or propylene glycol
Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.
Flagyl ER (metronidazole) side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
vision problems, pain behind your eyes;
weakness, confusion, slurred speech, problems with coordination;
trouble sleeping, depression, feeling irritable;
a light-headed feeling, like you might pass out;
fever, neck stiffness, increased sensitivity to light, purple spots on the skin;
numbness, tingling, or burning pain in your hands or feet;
severe stomach pain, diarrhea that is watery or bloody; or
blisters or ulcers in your mouth, red or swollen gums, trouble swallowing.
Side effects may be more likely in older adults.
Common side effects may include:
nausea, vomiting, loss of appetite, stomach pain;
unpleasant metallic taste;
vaginal itching or discharge;
mouth sores; or
swollen, red, or "hairy" tongue.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect Flagyl ER (metronidazole)?
Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.
Tell your doctor about all your current medicines and any you start or stop using, especially:
a blood thinner--warfarin, Coumadin, Jantoven.
This list is not complete. Other drugs may interact with metronidazole, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
See also: Side effects (in more detail)
More about Flagyl ER (metronidazole)
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Support Group
- En Español
- 6 Reviews – Add your own review/rating
- Generic Availability
- Drug class: amebicides
Related treatment guides
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.
- Disclaimer: 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.
Copyright 1996-2012 Cerner Multum, Inc. Version: 11.01.
Date modified: October 13, 2017
Last reviewed: August 28, 2017