Health Library

Metronidazole (By mouth)

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

Treats infections caused by bacteria or protozoa (including trichomoniasis and amebiasis).

Brand Name(s):

Flagyl 375, Likmez

When This Medicine Should Not Be Used:

How to Use This Medicine:

Capsule, Liquid, Tablet, Long Acting Tablet

• Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
• Capsule: Take with food or milk to avoid upset stomach.
• 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.
• Oral liquid: Shake the bottle well before using. Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.
• Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.
• Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
• 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 treatment.
• Some foods and medicines can affect how metronidazole works. Tell your doctor if you are using any of the following:
  • Busulfan, cimetidine, lithium, phenobarbital, phenytoin
  • Blood thinner (including warfarin)
  • Medicine that may cause heart rhythm problems

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, a yeast infection (including oral thrush), or a history of blood or bone marrow problems or seizures.
• Your doctor may tell you to stop breastfeeding, and pump and discard your breast milk for at least 48 hours after the last dose.
• This medicine may cause the following problems:
  • Brain or nervous system problems, including peripheral neuropathy, encephalopathy, seizures, meningitis, or vision problems
  • Liver problems, which may be life-threatening
  • Serious skin reactions
• Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.
• 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.
• 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
• Blistering, peeling, red skin rash
• Blurred vision, dizziness, problems with muscle control, clumsiness, shakiness, trouble talking
• Change in how much or how often you urinate
• Confusion, drowsiness, headache, stiff neck or back
• Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
• Fast, pounding, or uneven heartbeat, fainting, lightheadedness
• Fever, chills, cough, sore throat, body aches
• Numbness, tingling, or burning pain in your hands, arms, legs, or feet
• Seizures
• Unusual bleeding, bruising, or weakness
• Vaginal itching or discharge

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

• Sores or white patches on your lips, mouth, or throat
• 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: 9/6/2024