Augmentin vs. Flagyl
See how Augmentin and Flagyl compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Augmentin is a penicillin-type antibiotic for respiratory, ear, sinus, skin, and urinary infections, while Flagyl targets anaerobic bacteria and parasites like trichomoniasis and amebiasis.
Doctors sometimes prescribe Augmentin and Flagyl together to cover both aerobic and anaerobic bacteria in mixed infections, such as some abdominal or pelvic infections.
Flagyl carries a boxed warning about carcinogenicity in animal studies and cannot be combined with alcohol, while Augmentin's main risks are allergic reactions and liver effects.
Augmentin vs. Flagyl Drug Summary
Augmentin
Augmentin combines amoxicillin, a penicillin-class antibiotic, with clavulanate, which blocks a common bacterial resistance enzyme. It treats respiratory, ear, sinus, skin, and urinary tract infections caused by susceptible bacteria. It comes as a tablet, chewable tablet, or oral suspension taken every 8 or 12 hours.
Flagyl
Flagyl (metronidazole) is a nitroimidazole antibiotic that treats anaerobic bacterial infections and certain parasitic infections like trichomoniasis and amebiasis. It is also used off-label for bacterial vaginosis. It is taken as an oral tablet, typically two to four times daily depending on the infection.
Augmentin vs. Flagyl Side Effects
Augmentin
Flagyl
Augmentin vs. Flagyl Dosage
Augmentin
Flagyl
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg/125 mg every 8 hrs | At the start |
| Maximum dose | 2000 mg/125 mg every 12 hrs | If needed |
| Dose changes | 4 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg three times daily | Days 1-7 |
| Maximum dose | 7.5 mg/kg every 6 hours | Days 1-7 |
| Dose changes | 3 increases | As tolerated |
Augmentin
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg/125 mg every 8 hrs | At the start |
| Maximum dose | 2000 mg/125 mg every 12 hrs | If needed |
| Dose changes | 4 increases | As tolerated |
Flagyl
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg three times daily | Days 1-7 |
| Maximum dose | 7.5 mg/kg every 6 hours | Days 1-7 |
| Dose changes | 3 increases | As tolerated |
Augmentin vs. Flagyl Indications
Augmentin
Augmentin is FDA-approved for common bacterial infections including lower respiratory infections, ear infections, sinusitis, skin infections, and urinary tract infections. It is not effective against viral illnesses like colds. People with a history of penicillin allergy should avoid it.
Acute bacterial otitis media
Acute bacterial sinusitis
Community-acquired pneumonia (XR)
Skin and skin structure infections
Flagyl
Flagyl is FDA-approved for trichomoniasis, amebiasis, and anaerobic bacterial infections, and it is often used off-label for bacterial vaginosis. It works against parasites and bacteria that thrive without oxygen, which Augmentin does not typically cover. It should not be combined with alcohol during treatment.
Symptomatic and asymptomatic trichomoniasis
Amebiasis
Anaerobic bacterial infections
Bacterial vaginosis (off-label)
Augmentin vs. Flagyl Pros and Cons
Augmentin
Augmentin covers a broad range of common bacterial infections and has decades of pediatric use behind it. Its main downsides are a higher rate of diarrhea from the clavulanate component and the need for more frequent dosing with some formulations.
Pros
Broad coverage including beta-lactamase-producing resistant bacteria
Available as chewable tablets and suspension for children
No boxed warning
Once-daily XR option for pneumonia
Cons
Higher rate of diarrhea than many antibiotics
Not usable in people with penicillin allergy
Can cause liver problems in rare cases
Typically dosed 2-3 times daily for most formulations
Flagyl
Flagyl is highly effective against anaerobic bacteria and certain parasites that Augmentin does not treat, and some regimens allow a single-dose or short course. Its downsides include a strict no-alcohol rule and a boxed warning about carcinogenicity seen in animal studies.
Pros
Single-dose option for trichomoniasis
Effective against anaerobic infections Augmentin cannot treat
Low-cost generic tablets widely available
Shorter treatment courses for some infections
Cons
Boxed warning for carcinogenicity in animal studies
Cannot be combined with alcohol or disulfiram
Risk of seizures and nerve damage with prolonged use
Metallic taste is a common complaint
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