Buy Flagyl Online - Brand Name Metronidazole
Flagyl 500 mg
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Active Ingredient(s):
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Buy Flagyl (Metronidazole) Online  

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General Information About Onglyza

Flagyl is a highly effective oral synthetic antibiotic, antiprotozoal, and anaerobic antibacterial agent. Flagyl is the brand name under which Pfeizer manufactures and markets the prescription antibiotic medicine that features metronidazole as its active ingredient. Pfeizer’s Flagyl was approved for pharmaceutical use in 1963.

Metronidazole is known to be highly proficient in helping to combat bacterial infections in your body. Although it will not treat a vaginal yeast infection, Flagyl is used as a treatment for bacterial infections of the vagina, stomach, skin, joints, as well as the respiratory tract.

Flagyl may in fact be prescribed for purposes that are not listed here.

Active Ingredient

Metronidazole is the active ingredient in the Flagyl prescription drug. Metronidazole tablets contain 500 mg of the active ingredient, Metronidazole. Inactive ingredients of the drug include colloidal anhydrous silica, crospovidone, hydroxypropyl cellulose, hypromellose, iron oxide yellow, microcrystalline cellulose, polyethylene glycol, stearic acid and titanium dioxide.

Being the first member of the group of drugs now known as nitroimidazoles, Metronidazole was synthesized by France's Rhone-Poulenc laboratories. It was subsequently presented in the 1950s under the brand name Flagyl and licensed in the US to Searle.

How Does Metronizadole Work?

Metronidazole may be used in the treatment of anaerobic infections that are caused by bacteria or parasites that are vulnerable. “Anaerobic” denotes directly as "living without air". The compound is known to be active against these types of bacteria:

Gram-positive anaerobes (Clostridium species, Eubacterium species, Peptococcus species, Peptostreptococcus species)

Gram-negative anaerobes (certain Bacteroides fragilis group organisms, Fusobacterium species, Protozoalparasites, Entamoeba histolyticaTrichomonas vaginalis).

Once it is absorbed into the bloodstream, metronidazole disperses into vulnerable anaerobic organisms, where it is then condensed to its active form. The subsequent active form, as well as the free radicals that are also released, inhibit the synthesis of bacterial DNA and increase DNA degradation. This causes bacterial death. Metronidazole’s exact modus operandi is unknown.

Uses and Indications for Flagyl


These include peritonitis, intra-abdominal abscess, as well as liver abscess, that are caused by Bacteroides species including the B. fragilis group (B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron, B. vulgatus), Clostridium species, Eubacterium species, Peptococcus species, and Peptostreptococcus species.


Typical skin and/or structure infections that are caused by Bacteroides species including the B. fragilis group, Clostridium species, Peptococcus species, Peptostreptococcus species, and Fusobacterium species.


Common gynecologic infections including endometritis, endomyometritis, tubo-ovarian abscess, and postsurgical vaginal cuff infection, that are caused by Bacteroides species including the B. fragilis group, Clostridium species, Peptococcus species, Peptostreptococcus species and Fusobacterium species.


Typical bacterial septicemia that is caused by Bacteroides species including the B. fragilis group and Clostridium species.


Used as adjunctive therapy in bone and joint infections that are caused by Bacteroides species including the B. fragilisgroup.


These infections of the Central Nervous System include meningitis and brain abscess that are caused by Bacteroides species including the B. fragilis group.


Some common lower respiratory tract infections including pneumonia, empyema, and lung abscess that are caused by Bacteroides species including the B. fragilis group.


Endocarditis infection that is caused by Bacteroides species including the B. fragilis group.

Generic and Brand Name Medications(s)

Brand name(s): Flagyl (immediate-release), Flagyl ER (extended-release), Metrodinazole.

How To Take and Dosage information

Note: Metronidazole tablets should always be taken exactly as your doctor instucts you. In case of any uncertainty, it is advised to check with your doctor or pharmacist.

It is strongly advised that you do not to drink alcohol during the course of taking this medicine as well as for 48 hours after you have finished the course of tablets. This is due to the fact that taking alcohol whilst on metronidazole might cause unpleasant side-effects, such as a sense of or being sick, abdominal pain, palpitations, hot flushes and headache.

The tablets should be swallowed whole, during meals or after, with a glass of water. Do not chew the tablets.

Dosage Information

Treatment of bacterial infections

Adults and children over 10 years: an initial 800mg followed by a further 400mg at eight hourly intervals. 
The treatment instructions are usually to follow the dosage for 7 days but will depend upon your condition.

Treatment of anaerobic infections

Children 8 weeks-12 years: 20-30mg/kg/day as a single dose or divided into 7.5mg/kg at 8 hour intervals for 7 days. 
Children under 8 weeks: 15mg/kg/day as a single dose or divide the single dosage into 7.5mg/kg every 12 hours.

Treatment of infection caused by Trichomonas 

Adults and adolescents: 2g as a single dose, alternatively, 200mg three times per day for a total of 7 days, or 400mg twice a day for a minimum of 5 days and up to 7 days. Your partner should also be treated. 
Children under 10 years: 40mg/kg taken as a single dose or 15-30mg/kg/day between two to three times per day for 7 days.

Treatment of non-specific genital infection in women

Women: 400mg twice daily as a 7-day course, or 2g as a single dose for a single day. 
Adolescent girls: 400mg twice per day for between 5 to 7 A days or 2g as a single dosage.

Treatment of amoebiasis

Adults and children over 10 years: 400mgA 800mg three times daily for a minimum of 5 days to a maximum of 10 days. 
Children 7-10 years: 200mg-400mg three times daily for a minimum of 5 days to 10 days. 
Children 3 - 7 years: 100mg-200mg four times daily for a minimum of 5 days to 10 days. 
Children 1 -3 years: 100mg-200mg three times a day for a minimum of 5 days to 10 days. 
Otherwise, 35-50mg/kg/day divided into 3 doses for a minimum of 5 days to 10 days. 

Treatment of giardiasis

Adults and children over 10 years: 2g one times daily for 3 days, or 400mg thrice daily for 5 days or 500mg twice per day for 7 to 10 days. 
Children 7-10 years: 1g once daily for a total of 3 days. 
Children 3 - 7 years: between 600mg-800mg once per day for 3 days. 
Children 1-3 years: 500mg once daily for 3 days. 
Otherwise, 15-40mg/kg/day divided into two to three doses.

Other Treatments

Treatment of infections of the gums: 3 days

Treatment of infections of Teeth: 3-7 days 
Adults and children over 10 years: 200mg thrice daily.

Treatment of infected leg ulcers or pressure sores (for 7 days) 
Adults and children over 10 years: 400mg three times a day

Treatment of stomach ulcers caused by Helicobacter pylori 
The medicine is to be taken as instructed by your doctor as a part of a course with two additional medicines.

Prevention of infections after surgery 

Adults: 1g taken as a single dosage 24 hours before surgery followed by 400mg at 8 hourly intervals during the 24 hours after the operation.
Children under 12 years: 20-30mg/kg taken as a single dosage, approximately 1-2 hours before the operation. 
Newborn infants with a gestation age that is less than 40 weeks: An appropriate dosage form should be applied.

It is especially important that if you are elderly or have liver disease, to take this medicine precisely as instructed by your doctor.

If you exceed the directed dose

If you or someone else swallows many tablets at the same time, or if you think that a child may have swallowed any tablets, it is important to contact your nearest hospital casualty/emergency department or to tell your doctor immediately. Common signs of an overdose include a sense of or being sick, loss of appetite, diarrhea, a metallic taste in the mouth or on your tongue, headache, dizziness, insomnia or even drowsiness.

If you miss a dosage

You should not take a double dose to make up for the missed dose. If you miss a dose, you should take the dose as soon as you remember it and the next dose should be taken at the right time.

If you stop the course

If you stop the course before the recommended period, your infection may come back. Speak to your doctor before you stop the course and follow their advice.

Possible side effects

Similar to all other medicines, Metronidazole tablets have the potential to cause side effects. This may be especially applicable when you first start taking it, although not everyone develops them. Please speak to your doctor or pharmacist in case you notice any of the following effects or any effects not listed.

Possible Side-Effects

Any of these signs of an allergic reaction to metronidazole should be treated as adverse side-effects and medical assistance should be sought urgently:

  • Hives
  • Difficulty breathing
  • Swelling of your face, lips, tongue, or throat.
  •  In case you notice any of these serious side effects, your doctor should be called at once:
  • numbness or tingling in the hands or feet;
  • white spots or sores inside the mouth or on the lips;
  • pain or burning when urinating;
  • watery or bloody diarrhea;
  • pain behind your eyes or any other vision problems;
  • if you are having trouble concentrating, have slurred speech, notice any mood or behavior changes, tremors, muscle twitching and/or seizure (convulsions);
  • the presentation of fever, chills, muscle pain, confusion, headache, sore throat, neck stiffness, heightened sensitivity to light, drowsiness, nausea and vomiting; or
  • severe skin reaction
  • fever, sore throat, swelling in the face or tongue, burning in the eyes
  • Skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.


Less serious side effects of Flagyl (metronidazole) may include:

  • stomach pain, diarrhea;
  • dizziness, loss of balance;
  • vaginal itching or discharge;
  • dry mouth or unpleasant metallic taste;
  • coughing, sneezing, runny or stuffy nose; or
  • swollen or sore tongue.


Warnings and Precautions



This medication should not be used if there is a known allergy to metronidazole.

Metronidazole should not be used in the first trimester of pregnancy. It is important to alert your doctor if you are pregnant or if you plan to become pregnant during the course of treatment.

Metronidazole can pass into breast milk though the blood stream and may harm a nursing baby. If you are breast-feeding a baby, it is important that you do not take the drug without notifying your doctor about the fact that you are breastfeeding.




You may need a dosage modification or specific tests to safely take this medication If you have any of the following conditions:


  • liver disease;
  • a gastrointestinal disease such as Crohn's disease;
  • a blood cell illness such as anemia, or leukopenia;
  • epilepsy or other seizure disorders; or
  • nerve disorders.

Note: It is important to notify your doctor if you are allergic to any drugs, or if you have any of these aforementioned conditions before taking metronidazole.


Frequently Asked Questions

What other drugs will interact with metronidazole?

It is important to tell your doctor about all and any other medicines you use; this includes prescription medicine, over-the-counter, vitamin, and/or herbal products. It is especially important if you use any of the following:

  • cimetidine (Tagamet);
  • seizure treatment such as phenytoin (Dilantin) or phenobarbital (Luminal, Solfoton);
  • a blood thinner medication such as warfarin (Coumadin, Jantoven);
  • lithium (Lithobid, Eskalith, others); or
  • disulfiram (Antabuse).

This list is not complete and other drugs may interact with metronidazole. Tell your doctor about all medications you use. Do not start any new medication without telling your doctor while on treatment with metronidazole.

What is Flagyl?

Flagyl is an antibiotic and antiprotozoal medication.

How does Flagyl work?

The exact way in which Metronidazole works is unknown. Once the drug is absorbed into the bloodstream, metronidazole disperses into susceptible anaerobic organisms, and then condensed to its active form. The active form, as well as the free radicals that are released, inhibit the synthesis of bacterial DNA and increase DNA degradation. This causes bacterial death.

How do I Store Flagyl?

Keep metronidazole out of the reach and sight of children.

Store below 25 degrees Celsius and protect from light. Metronidazole tablets should not be used after the expiry date that is stated on the packaging. The expiry date refers to the last day of that month. Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist about proper disposal measures to ensure safety.

Is Flagyl called differently in USA than in Canada?

The international brand name for metronidazole manufactured by Pfeizer is Flagyl.