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Metronidazole (By mouth)

Metronidazole (met-roe-NYE-da-zole)

Treats bacterial infections.

Brand Name(s):

Flagyl, Flagyl 375, Flagyl ER, Helidac Therapy

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use if you had an allergic reaction to metronidazole or similar medicines. Do not use this medicine to treat trichomoniasis if you are in the first 3 months of pregnancy.

How to Use This Medicine:

Capsule, Tablet, Long Acting Tablet

  • Take this medicine as directed, and take it at the same time each day.
  • Capsule or Tablet: Take with food or milk to avoid stomach upset.
  • Extended-release tablet: Take it on an empty stomach, 1 hour before or 2 hours after a meal.
  • Swallow the extended-release tablet whole. Do not crush, break, or chew it.
  • Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.
  • Missed dose:Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not use this medicine if you have taken disulfiram within the last 2 weeks. Do not drink alcohol or use medicine that contains alcohol or propylene glycol while using this medicine and for at least 3 days after you have finished metronidazole treatment.
  • Some foods and medicines can affect how metronidazole works. Tell your doctor if you are using busulfan, cimetidine, lithium, phenobarbital, phenytoin, or warfarin or another blood thinner.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, blood or bone marrow problems, oral thrush, yeast infection, or a history of seizures.
  • This medicine may cause the following problems:
    • Brain or nervous system problems, including seizures, meningitis, or vision problems
  • Trichomoniasis treatment: Your doctor may want to also treat your sexual partner, even if he or she has no symptoms. Also, you may want to use a condom during sexual intercourse. These measures will help keep you from getting the infection back again from your partner. If you have any questions, ask your doctor.
  • Call your doctor if your symptoms do not improve or if they get worse.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Confusion, drowsiness, fever, headache, loss of appetite, nausea or vomiting, stiff neck or back
  • Dizziness, problems with muscle control, clumsiness, shakiness, trouble talking
  • Fever, chills, cough, sore throat, and body aches
  • Numbness, tingling, or burning pain in your hands, arms, legs, or feet
  • Seizures

If you notice these less serious side effects, talk with your doctor:

  • Mild nausea
  • Unusual or unpleasant taste in your mouth

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088


Last Updated: 4/4/2014

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