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AHFS Consumer Medication Information [Internet]. Bethesda (MD): American Society of Health-System Pharmacists; 2000-2011.

AHFS Consumer Medication Information.

Metronidazole Oral(me troe ni' da zole)

Last reviewed: September 1, 2010.

Warning

Metronidazole can cause cancer in laboratory animals. Talk to your doctor about the risks and benefits of using this medication.

Why is this medication prescribed?

Metronidazole eliminates bacteria and other microorganisms that cause infections of the reproductive system, gastrointestinal tract, skin, vagina, and other areas of the body. Antibiotics will not work for colds, flu, or other viral infections.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

How should this medicine be used?

Metronidazole comes as a tablet to take by mouth. It is usually taken two or three times a day for 5 to 10 days or longer. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take metronidazole exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

What special precautions should I follow?

Before taking metronidazole,

  • tell your doctor and pharmacist if you are allergic to metronidazole or any other drugs.

  • tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially anticoagulants ('blood thinners') such as warfarin (Coumadin), astemizole (Hismanal), disulfiram (Antabuse), lithium (Lithobid), phenobarbital, phenytoin (Dilantin), and vitamins.

  • tell your doctor if you have or have ever had blood, kidney, or liver disease or Crohn's disease.

  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking metronidazole, call your doctor.

  • know that you should not drink alcohol while taking this drug. Alcohol may cause an upset stomach, vomiting, stomach cramps, headaches, sweating, and flushing (redness of the face).

  • plan to avoid unnecessary or prolonged exposure to sunlight and to wear protective clothing, sunglasses, and sunscreen. Metronidazole may make your skin sensitive to sunlight.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What side effects can this medication cause?

Metronidazole may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • vomiting

  • diarrhea

  • upset stomach

  • loss of appetite

  • dry mouth; sharp, unpleasant metallic taste

  • dark or reddish-brown urine

  • furry tongue; mouth or tongue irritation

  • numbness or tingling of hands or feet

If you experience any of the following symptoms, call your doctor immediately:

  • rash

  • itching

  • stuffy nose

  • fever

  • joint pain

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/Safety/MedWatch] or by phone [1-800-332-1088].

What storage conditions are needed for this medicine?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to metronidazole.

Do not let anyone else take your medication. Your prescription is probably not refillable. If you still have symptoms of infection after you finish the metronidazole, call your doctor.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS® Consumer Medication Information. © Copyright, 2011. The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

The following brand names are from RxNorm, a standardized nomenclature for clinical drugs produced by the National Library of Medicine:

Brand names

  • Flagyl

  • Metryl

  • Protostat

What works?

  • Several antibiotic agents, including metronidazole, ciprofloxacin, and rifaximin, as well as oral probiotics, may be effective treatments for pouchitis. Several antibiotic agents, including metronidazole, ciprofloxacin, and rifaximin, as well as oral probiotics, may be effective treatments for pouchitis.
    Some patients with ulcerative colitis have their colon and rectum removed with construction of a reservoir or pouch (made from a loop of small intestine) to serve in place of the rectum. This is known as an ileal pouch‐anal anastomosis (IPAA) surgery. Pouchitis is acute inflammation of the surgically constructed pouch which may cause diarrhea and other problems. The exact cause of pouchitis is not known, but it may be caused by an imbalance in bacteria (similar to an infection) and can be treated by antibiotics, probiotics (bacteria important for the health of the bowel), or other agents that may reduce or prevent inflammation. Metronidazole and Ciprofloxacin (two antibiotics), budesonide enemas (a topical steroid that may decrease inflammation), and oral probiotic therapy with VSL#3 all appear to be effective therapies for acute and/or chronic pouchitis. Current evidence does not support the use of lactobacillus GG (a different probiotic), bismuth (a metal that may be useful in some diarrheal disorders), butyrate and glutamine (two nutrients required by the bowel), allopurinol (a gout medication which may decrease inflammation), or inulin (a non‐absorbable sugar which may decrease inflammation). So far the research performed has generally consisted of small studies that were not reproduced, so more research is needed to determine which of these different medications are best for treatment of pouchitis.
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