Flagyl (Metronidazole Generic Name): Effectiveness, Doses, Side Effects

Generic Flagyl (Metronidazole)
Containing the active ingredient metronidazole, Flagyl is a medication with strong antibacterial and antiprotozoal properties, highly effective in combating a variety of bacterial and parasitic infections. Its efficacy has been extensively demonstrated in the management of various illnesses caused by these pathogens.
Generic Flagyl (Metronidazole) 200mg
Compare price
200mg x 30 pills
200mg x 60 pills
200mg x 90 pills
200mg x 120 pills
200mg x 360 pills
400mg x 60 pills
400mg x 90 pills
400mg x 120 pills
400mg x 180 pills
400mg x 360 pills

The widest spread problems are those affecting the skin, genitals, bones and joints, neurological system etc. Additionally, sex-related illnesses (STDs) are treated with this medication. Women who have bacterial vaginosis, an infection brought on by an overabundance of dangerous bacteria in the vagina, are usually prescribed Flagyl as the main treatment course. Flagyl helps not only with problems associated with women’s health, but also with various infections, and diseases caused by protozoa.


This medication is exclusively effective against bacterial infections; it is ineffective against viral illnesses such as the cold and the flu. This tool is universal and effective against the following diseases:

  • Bacterial Vaginosis as well as Amebiasis.
  • Bacillus coli.
  • Dentenemoeba fragilis.
  • Giardiasis.
  • Hodgkin’s lymphoma Infection.
  • Gastrointestinal infection.
  • Infected of joints.
  • Uncomplicated urethritis.
  • Pelvic inflammatory disease, osteomyelitis.
  • Pseudomembranous Colitis and Peritonitis.
  • Trichomoniasis.
  • Infection caused by different bacteria.
  • Body and Skin Infection.
  • Surgical Precautions.
  • STD Prevention.

Is Flagyl effective against Helicobacter Pylory?

Flagyl at Canadian Pharmacy Drug is recommended as one of the antibiotics for the eradication of Helicobacter pylori. However, in Canada, due to the widespread and not always correct use of metronidazole, the level of resistance to metronidazole is almost twice as high as in Europe: 55.5% in Canada and 25.5% in Europe.

Also, according to the modern Canadian Standards for the Diagnosis and Treatment of Acid-Dependent and Helicobacter pylori-Associated Diseases, Flagyl is allowed only in one of the “second line” regimens (used if the patient had unsuccessful treatment of Helicobacter pylori according to one of the “first line” regimens). In this case, the following treatments are prescribed: Flagyl 500 mg 3 times a day, bismuth tripotassium dicitrate 120 mg 4 times a day, tetracycline 500 mg 4 times a day and one of the proton pump inhibitors at the standard dosage (omeprazole 20 mg, lansoprazole 30 mg, pantoprazole 40 mg, esomeprazole 20 mg, rabeprazole 20 mg twice a day) for 10–14 days.

Mechanism of Action

Flagyl is a fast acting medicine, that is almost completely absorbed in a short period of time. Flagyl mechanism of action lies in the biochemical degradation of the 5-nitro group of metronidazole by intracellular anaerobic and naturally existing transport proteins. It is believed that the decreased 5-nitro group of metronidazole will interact with DNA in body cells and prevent the creation of their nucleic acids. Additionally, the primary metabolite, 2-oxymetronidazole, exhibits antiprotozoal and antibacterial properties.

What are the side effects?

Like every medical drug, Flagyl has a number of contraindications and side effects. Actually, the list of potential adverse effects is pretty long, but still, the most common are: nausea, a pungent taste in the mouth, anorexia, epigastric pain, vomiting, diarrhea, headache, dizziness, allergic reactions (urticaria, itching), leukopenia, peripheral neuropathy, with prolonged exposure to doses, brown-reddish staining of the urine.

Talking about contradictions, Flagyl should not be used during pregnancy and breastfeeding. It’s also not recommended to give the medicine to patients in the case of liver failure (when excessive doses are used), intolerance to any component of the drug, leukopenia, or organic diseases of the central nervous system (including epilepsy).


Flagyl pills are swallowed whole, without chewing, with food or immediately after eating. It’s possible to take the medicine with milk. The tablets have a bitter taste and must be taken with a sufficient amount of liquid.


  • If you have Trichomonas vaginalis infection, take 250 mg four times daily for five days;
  • If you have Entamoeba histolytica infection, take 2 g once or 250 mg twice daily for ten days. Adults: 750 mg three times daily for five to ten days, children — 35–50 mg per kg of body weight during 10 days max.
  • Children with Lamblia (Giardia intestinalis) infection: the daily dose is divided into two doses. The duration of therapy is 5–10 days; a second course of treatment is prescribed after 4–6 weeks. The dose varies on age: youngsters from 2 to 5 should take 250 mg daily, youngsters ages 6 to 10 — every day 375 mg.
  • Flagyl should be administered for no more than seven days to treat infections brought on by anaerobic bacteria. Flagyl may be used in conjunction with other antibiotics. Patients over 12 years old should first receive 1 g once, and then 250 mg three times each day.

Adults are prescribed vaginal suppositories. Flagyl therapy shouldn’t continue longer than 10 days and shouldn’t be given more than twice or three times a year. With trichomonas vaginitis, one suppository per day is used for 7–10 days in conjunction with the ingestion of Flagyl tablets; for non-specific vaginitis and bacterial vaginosis, one vaginal suppository per day for 7 days, if necessary, in conjunction with oral Flagyl tablets. The dosage and duration of use depend on the disease. You can buy Flagyl in any online or offline Canadian pharmacy, if you have necessary prescription.

Drug interactions

Flagyl does not interact well with alcohol, so alcohol should be excluded during the course of treatment.

The drug, interacting with different substances, has different effects:

  • Disulfiram: development of neurological symptoms. These drugs should be given at least 2 weeks apart.
  • Indirect anticoagulants: enhance the action, increas the time of prothrombin’s formation.
  • Lithium preparations: increase in plasma lithium concentration.
  • Cyclosporine: Plasma concentration of cyclosporine.
  • Cimetidine: increases the risk of side effects.
  • Phenobarbital, phenytoin: a decrease in the concentration of metronidazole in the blood.
  • Metronidazole: increases the toxicity of the drug.
  • The combination of Flagyl with non-depolarizing muscle relaxants is not recommended.

Treatment with Flagyl does not require discontinuation during menstruation. In the treatment of Trichomonas vaginitis should refrain from sexual intercourse. After the end of treatment for the next 3 cycles, control samples are taken before and after menstruation.

If neurological symptoms (hallucinations, ataxia, dizziness) appear, the drug should be discontinued. Because of these possible side effects, it is advisable to refrain from driving. Timely treatment will help to avoid complications and the transition of the disease into a chronic form in the future.