Metronidazole vs. Flagyl
See how Metronidazole and Flagyl compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Metronidazole and Flagyl contain the exact same active ingredient, so their effects, risks, and drug interactions are identical.
Flagyl brand-name tablets have been discontinued in the US, so generic metronidazole is now the only way to get this medication as a tablet.
Both carry the same boxed warning about carcinogenicity in animal studies and the same contraindications with alcohol and disulfiram.
Metronidazole vs. Flagyl Drug Summary
Metronidazole
Metronidazole is a nitroimidazole antibiotic used to treat trichomoniasis, amebiasis, bacterial vaginosis, and serious anaerobic bacterial infections. It comes as an oral tablet or capsule, with IV, topical, and vaginal forms available depending on the infection being treated.
Flagyl
Flagyl is the original brand name for metronidazole, a nitroimidazole antibiotic used to treat trichomoniasis, amebiasis, and anaerobic bacterial infections. The brand-name tablet has been discontinued, so Flagyl now refers mainly to the generic oral and IV metronidazole that replaced it.
Metronidazole vs. Flagyl Side Effects
Metronidazole
Flagyl
Metronidazole vs. Flagyl Dosage
Metronidazole
Flagyl
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg 3x daily | Days 1-7 |
| Maximum dose | 500-750 mg 3x daily | If needed |
| Dose changes | 2 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg 3x daily | Days 1-7 |
| Maximum dose | 7.5 mg/kg every 6 hrs | Days 1-7 |
| Dose changes | 3 increases | As tolerated |
Metronidazole
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg 3x daily | Days 1-7 |
| Maximum dose | 500-750 mg 3x daily | If needed |
| Dose changes | 2 increases | As tolerated |
Flagyl
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg 3x daily | Days 1-7 |
| Maximum dose | 7.5 mg/kg every 6 hrs | Days 1-7 |
| Dose changes | 3 increases | As tolerated |
Metronidazole vs. Flagyl Indications
Metronidazole
Metronidazole is FDA-approved for a wide range of infections, including trichomoniasis, amebiasis, bacterial vaginosis, and serious intra-abdominal infections like peritonitis and abscesses. It's also used off-label for H. pylori eradication and C. diff infections.
Trichomoniasis (symptomatic and asymptomatic)
Amebiasis
Bacterial vaginosis
Intra-abdominal infections (peritonitis, abscess)
Rosacea (topical form)
Flagyl
Flagyl was originally approved for trichomoniasis, amebiasis, and anaerobic bacterial infections, including treatment of the partners of people diagnosed with trichomoniasis. It's sometimes used off-label for bacterial vaginosis, though that regimen wasn't part of its original approval.
Trichomoniasis (symptomatic and asymptomatic)
Treatment of partners of trichomoniasis patients
Amebiasis
Anaerobic bacterial infections
Bacterial vaginosis (off-label)
Metronidazole vs. Flagyl Pros and Cons
Metronidazole
Because metronidazole is the generic form, it comes in more formulations and is FDA-approved for a broader set of infections than the original Flagyl label covered. It remains one of the most affordable and widely stocked generic antibiotics.
Pros
Available as oral, IV, topical gel, and vaginal gel
FDA-approved for bacterial vaginosis and rosacea
Approved for intra-abdominal infections like peritonitis
Cons
Generic tablets can look different between refills or pharmacies
No brand-name version is currently marketed in the US
Multiple formulations can make dosing selection more complex
Flagyl
Flagyl was the original brand for metronidazole, but the manufacturer discontinued brand-name tablets, so prescriptions now rely on generic versions. Its original approval was narrower than current generic labeling, excluding bacterial vaginosis and rosacea.
Pros
Includes an FDA-approved weight-based IV regimen for anaerobic infections
Original label covers treating asymptomatic partners of trichomoniasis patients
Extended-release tablet formulation available under this drug name
Cons
Brand-name Flagyl tablets are discontinued and unavailable
Original FDA approval doesn't include bacterial vaginosis or rosacea
Narrower set of FDA-approved indications than current generic labeling
Common Symptoms and Related Diseases You Can Explore
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