1 What is metronidazole?

Brand: Flagyl

Generic: Metronidazole Tablet

Metronidazole, or Flagyl, is a drug used in the treatment of trichomoniasis, amebiasis, and anaerobic bacterial infections. This drug is available as a tablet containing 250 mg or 500 mg of metronidazole.

Metronidazole is a fast acting medication that is only available as a prescription drug. It is an oral medicine that is available in two forms: both immediate-release tablet and extended-release tablet. The immediate-release table is fast-acting and is released in the body immediately after consumption. On the other hand, the extended-release tablet acts slowly over a period of time.

This medication only works for bacterial infections and is not to be used for viral infections such as cold and flu.

The tablets are available as generic medications and more commonly sold under the brand name Flagyl. The medication available under the generic name may be cheaper than the one sold under the brand name, but the dosage may be different for both, which would need to be checked by the doctor.

Metronidazole tablets are normally used along with other medications and do not act by themselves. It is therefore important to follow your doctor's instructions exactly.

Metronidazole is also easily available in the form of a cream or gel that is for topical application in case of skin infections or vaginal infections.

What conditions does metronidazole treat?

Metronidazole immediate-release oral tablets mainly are recommended to treat various types of bacteria and parasites that cause infections in the human body. Most of these infections triggered by these bacteria and parasites attack the gastrointestinal tract and the reproductive system in females.

The extended release tablets are normally recommended in case of vaginal infections affecting women.

Metronidazole is also used as a topical application for treating bacterial infections on the skin and the vagina. One condition that metronidazole is popularly used for is known as bacterial vaginosis. It is an infection in the vaginal area that is triggered due to an uncontrolled bacterial growth. One of the main symptoms of this condition are vaginal discharge with a foul smell. In a few cases the infection could clear up on its own and may not require any specific medication. However, in most cases, antibacterial gels like metronidazole may be prescribed. The gel can be applied in the vagina using a vaginal applicator.

Metronidazole could also be recommended with other medicines in the course of treating infections of the stomach or intestine that are caused by bacteria like H. Pylori.

What is Metronidazole?


You should read the product information leaflet before using this medication. If you have any questions, ask your doctor or pharmacist.

This medication should be taken by mouth as instructed by your doctor. Do not crush or chew the drug because it may diminish its effects. This medication should be taken with a full glass of water unless your doctor tells you otherwise. You should swallow the drug whole.

Your dosage is based on your medical condition and the way you will respond to treatment. Take this drug regularly to experience the most benefits. You should also take this drug at the same time each day.

If you miss a dose, use it as soon as you remember. Continue to use it as prescribed by your doctor or as stated on the package label.


Metronidazole tablet may interact with medications such as:

  • Alcohol-containing products such as:
    • Cough syrups
    • Cold syrups
    • Aftershave
  • Amprenavir oral solution
  • Disulfiram
  • Lopinavir or ritonavir oral solution
  • Blood thinners such as:
    • Warfarin
  • Busulfan
  • Cimetidine
  • Fluorouracil
  • Lithium
  • Mebendazole
  • Live bacterial vaccines
  • Drugs for seizures such as:
    • Phenobarbital
    • or Phenytoin

Side effects

There are no side effects known aside from a possible allergic reaction in people who have previous or unknown hypersensitivity to the drug. However, some of the common side effects that one may face when consuming this drug for the first time are dizziness or fainting, disturbed stomach, nausea or vomiting, loss of hunger, diarrhea, or constipation.

Urine could turn dark yellow in some people, but it is a relatively common symptom and not a cause of concern. The effect usually disappears once the medicine has been stopped.

Consuming this medicine for a long period of time could put you at a risk of new forms of infections like oral thrush or yeast infection. In case you do notice white patches in your mouth or symptoms of vaginal infection, then speak to your doctor immediately.

Watch out for signs of allergic reactions such as:

  • Rash
  • Itching
  • Swelling

It is important to remember that this medicine is prescribed by your doctor because he or she thinks the benefits outweigh the risks of side effects. If you are facing any serious side effects, then it is always better to go back to your doctor and discuss the same.


Before consuming metronidazole, speak to your doctor if you are allergic to the medicine or any of the ingredients of the medication. The product contains a few ingredients that could cause an allergic reaction for some people. Discuss the same with your doctor.

Before you start this medicine, always discuss your medical history with your doctor, particularly if you are suffering from any serious health condition like a kidney disorder, liver dysfunction, and forms of blood disorders.

When you are on this medication, avoid the consumption of alcoholic beverages. Wait until you have completed the course of your medication. This medicine could trigger cramps, nausea, upset stomach, and other such conditions when mixed with alcohol.

This drug could cause some people to feel dizzy and it is advisable to avoid activity that may require concentration, such as driving or operating any heavy machines.

In case of pregnant women, this medicine should be taken only when absolutely required. Although there are no threats of using this medication for pregnant women, it is always advisable to consult your doctor about the associated risks.

In case of lactating mothers, this medicine could pass to the baby through breast milk. Therefore, if you are breast feeding, discuss the possible risks and benefits with your doctor. If you are prescribed the medicine for a short term and for a single dose, then the doctor may tell you not to breastfeed immediately after having the medicine. 

Before taking this medication, tell your doctor or pharmacist if you have the following:

  • Allergy to metronidazole or to other nitroimidazoles such as:
    • Tinidazole
  • Liver problems
  • Nervous system disorders such as:
    • Seizures
  • Blood disorders
  • Crohn's disease
  • Pregnancy or lactation

It is important to remember that this medicine is prescribed for a specific condition only, and should not be taken on one’s own will even if it for the same condition. Always seek doctor’s advice before starting or re-starting this medication. In case of a number of infections, sexual interaction may be an added risk of transmitting the infection to others. Always use protection in such cases to avoid aggravating your own situation and to refrain from transmitting your infection to others.

Metronidazole for pets

Metronidazole is also a highly recommended medication in case of pets to treat problems like swelling in the large intestine that could be triggered due to a bacterial infection. It is also known to be highly effective against a number of bacterial infections like Giardia, Trichomonas, and Balantidium coli. Metronidazole may be given along with other antibiotics even in case of pets to treat the infection completely.

Metronidazole is highly effective in treating infections of the central nervous system. It is highly beneficial in treating infections associated with bones and teeth in case of pets. This medication should be given to pets along with food to enhance its absorption and to prevent an upset stomach.

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