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Flagyl

(metronidazole)

In this factsheet:
• How does Flagyl work? What will it do for me?
• How should I use Flagyl?
• What form(s) does Flagyl come in?
• Who should NOT take Flagyl?
• What side effects are possible with Flagyl?
• Are there any other precautions or warnings for Flagyl?
• What other drugs could interact with Flagyl?

DIN (Drug Identification Number)

What side effects are possible with Flagyl?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea
• dizziness or lightheadedness
• headache
• loss of appetite
• nausea or vomiting
• stomach pain or cramps

Less common or rare:

• change in taste sensation
• dryness of mouth
• unpleasant or sharp metallic taste

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Less common:

• any vaginal irritation, discharge, or dryness not present before use of this medicine
• black, tarry stools
• blood in urine or stools
• clumsiness or unsteadiness
• frequent or painful urination
• inability to control urine flow
• mood or other mental changes
• nausea and vomiting
• pinpoint-sized red spots on skin
• sense of pelvic pressure
• skin rash, hives, redness, or itching
• sore throat and fever
• stomach and back pain (severe)
• unusual bleeding or bruising

Check with your doctor immediately if any of the following side effects occur:

Less common:

• numbness, tingling, pain, or weakness in hands or feet

Rare:

• convulsions (seizures)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for Flagyl?

Be sure to inform your doctor of all your medical conditions before you begin taking a medication. Some conditions can affect how you should take this medication.

Alcohol: A severe set of side effects including nausea and vomiting may occur if you consume alcohol while taking metronidazole. People taking this medication should wait until at least one day after finishing metronidazole treatment before drinking alcohol.

Confusion/dizziness: This medication may cause confusion or dizziness. Avoid driving or other tasks requiring alertness if the medication affects you in this way.

Diarrhea: If diarrhea occurs while taking metronidazole, consult your doctor.

Liver disease: People with severe liver disease should be closely monitored by their doctor while taking metronidazole.

Neurological side effects: Stop treatment with metronidazole and see your doctor if muscle incoordination, seizures, or numbness or tingling in the hands or feet occur.

Pregnancy: Although this medication has been taken by pregnant women without apparent complication, it is advisable to avoid taking metronidazole during pregnancy and not to take it at all during the first trimester of pregnancy. If the medication is considered necessary, the potential benefits must be weighed against the possible risks. If you are or may be pregnant, speak to your doctor about the risks and benefits of using metronidazole.

Breast-feeding: Metronidazole passes into breast milk. It should not be taken by women who are breast-feeding.

Children: Experience with the use of this medication by children is very limited. If metronidazole is used by children, they should be carefully monitored by their doctor.

What other drugs could interact with Flagyl?

The following medications may affect how metronidazole works or increase the risk of side effects:

• alcohol
• barbiturates (e.g., phenobarbital, primidone, butalbital)
• disulfiram

Metronidazole may affect how the following medications work:

• lithium
• phenytoin
• vecuronium
• warfarin
• 5-fluorouracil

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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