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Flagyl Patient Tips

Written by C. Fookes, BPharm on May 29, 2017

How it works

  • Flagyl is a brand (trade) name for metronidazole.
  • Metronidazole is an antibiotic that may be used in the treatment of anaerobic infections caused by bacteria or protozoa. Anaerobic means "living without air".


  • Treats a wide range of infections such as those occurring in the abdomen, gastrointestinal tract, in the deeper layers of the skin, genitourinary area, in bones or joints, throughout the blood, in the central nervous system, heart and lower respiratory tract.


If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • A headache, nausea, diarrhea, an unpleasant metallic taste, peripheral neuropathy (nerve damage to fingers and toes), or a rash are common side effects. Rarely, seizures.
  • Flagyl reacts with alcohol. Symptoms include abdominal cramps, nausea, vomiting, headaches, and flushing. Avoid alcohol while taking Flagyl.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

Bottom Line

Flagyl is an antibiotic that is particularly effective at treating anaerobic infections. Avoid alcohol while taking Flagyl and for three days after stopping it.


  • May be taken with or without food.
  • Avoid alcohol while taking Flagyl, and for three days after you have finished your course of Flagyl.
  • Take exactly as directed and for the duration intended.
  • Only use when prescribed by a doctor to treat infections caused by susceptible bacteria as improper use increases the chance of resistant bacteria developing.
  • Seek medical advice if numbness, pain, or sensitivity occurs in your fingers or toes, or if you notice any skin color changes in these areas.

Response and Effectiveness

Peak concentrations are reached within one to two hours after dosing; however, it may take up to 48 hours before infection-related symptoms start to abate.


Flagyl [Package Insert]. Revised 07/2016. G.D. Searle LLC Division of Pfizer Inc

  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use flagyl only for the indication prescribed.

  • Disclaimer: Every effort has been made to ensure that this information is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This drug information does not endorse drugs, diagnose patients or recommend therapy. It is an informational resource designed 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. does not assume any responsibility for any aspect of healthcare administered with the aid of this information. 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 1996-2017 Revision Date: 2017-05-29 21:18:17