Augmentin vs. Metronidazole

See how Augmentin and Metronidazole compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Augmentin covers a broad range of bacteria and is the go-to for sinus, ear, lung, skin, and urinary infections, while metronidazole targets anaerobic bacteria and certain parasites.

  • Metronidazole requires strict alcohol avoidance due to a disulfiram-like reaction, while Augmentin's main risks are diarrhea and, rarely, liver injury.

  • Metronidazole is generally more affordable than Augmentin at typical pharmacy list prices, though both are widely covered by insurance.

Augmentin vs. Metronidazole Drug Summary

Augmentin

Augmentin combines amoxicillin, a penicillin-class antibiotic, with clavulanate, which blocks the bacterial enzymes that would otherwise destroy amoxicillin. It treats a wide range of bacterial infections, including ear, sinus, lung, skin, and urinary infections. It comes as tablets, chewables, or liquid, usually taken two or three times a day with food.

Metronidazole

Metronidazole is a nitroimidazole antibiotic that targets anaerobic bacteria and certain parasites rather than the broad bacterial range Augmentin covers. It's the standard treatment for infections like bacterial vaginosis, trichomoniasis, and intra-abdominal abscesses caused by anaerobes. It's taken as an oral tablet or capsule, typically two to four times a day, and alcohol must be avoided during treatment.

Augmentin vs. Metronidazole Side Effects

Augmentin

Most common
diarrhea (up to 9%)
nausea (up to 3%)
skin rash/urticaria (up to 3%)
vomiting (up to 1%)

Metronidazole

Most common
nausea (most common)
headache (commonly reported)
anorexia (commonly reported)
metallic taste (often reported)

Augmentin vs. Metronidazole Dosage

Augmentin

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 250 mg/125 mg q8h At the start
Maximum dose 2000 mg/125 mg q12h If needed
Dose changes 4 increases As tolerated

Metronidazole

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 250 mg three times daily Days 1-7
Maximum dose 500-750 mg three times/day If needed
Dose changes 2 increases As tolerated

Augmentin vs. Metronidazole Indications

Augmentin

Augmentin is FDA-approved for common bacterial infections of the ears, sinuses, lungs, urinary tract, and skin. Its added clavulanate component lets it work against bacteria that have become resistant to amoxicillin alone.

  • Lower respiratory tract infections

  • Acute bacterial otitis media

  • Acute bacterial sinusitis

  • Skin and skin structure infections

  • Urinary tract infections

Metronidazole

Metronidazole is FDA-approved for infections caused by anaerobic bacteria and certain parasites, including trichomoniasis, amebiasis, and bacterial vaginosis. It's also used off-label, usually combined with other drugs, for H. pylori and C. difficile infections.

  • Trichomoniasis

  • Bacterial vaginosis

  • Amebiasis

  • Intra-abdominal infections (abscess, peritonitis)

  • Anaerobic bacterial infections

Augmentin vs. Metronidazole Pros and Cons

Augmentin

Augmentin's added clavulanate lets it fight bacteria that produce enzymes resistant to plain amoxicillin, making it useful for a wide range of common infections. It's a well-established first-line option with pediatric-friendly forms and no FDA boxed warning.

Pros

  • Covers a much broader range of bacteria, including beta-lactamase producers

  • Available in chewable tablets and pediatric suspension formulations

  • No FDA boxed warning, unlike metronidazole's carcinogenicity warning

  • First-line option for common ear, sinus, and urinary tract infections

Cons

  • More likely to cause diarrhea and stomach upset than metronidazole

  • Unsafe for anyone with a history of penicillin allergy or amoxicillin-related liver injury

  • Carries a rare but serious risk of hepatotoxicity

  • Typically costs more, roughly $80 to $150 per month without insurance

Metronidazole

Metronidazole works differently, targeting anaerobic bacteria and parasites that Augmentin can't reach, making it the standard treatment for certain gynecologic and abdominal infections. It's an older, well-established drug, but it carries unique warnings around alcohol use and nervous system side effects.

Pros

  • First-line treatment for trichomoniasis and bacterial vaginosis, which Augmentin doesn't treat

  • Effective against anaerobic infections that don't respond to penicillin-class drugs

  • Roughly $15 to $40 per month without insurance, often cheaper than Augmentin

  • Available in oral, IV, topical, and vaginal forms

Cons

  • Carries an FDA boxed warning for carcinogenicity seen in animal studies

  • Must avoid alcohol during treatment and for several days after due to a severe reaction

  • Risk of neurologic side effects like seizures, peripheral neuropathy, and encephalopathy

  • Doesn't treat common respiratory, sinus, or ear infections that Augmentin covers

Common Symptoms and Related Diseases You Can Explore

Explore a range of common symptoms the Doctronic Symptom Checker can help you understand.