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Compare Metronidazole vs. Amoxicillin

Head-to-head comparisons of medication uses, side effects, warnings, and more.

Key takeaways

Metronidazole (Flagyl) and amoxicillin (Amoxil) are both antibiotics used to treat bacterial infections, but they belong to different medication classes. Metronidazole is a nitroimidazole antibiotic, while amoxicillin is a penicillin antibiotic. Metronidazole is used for a variety of infections, including bacterial vaginosis and trichomoniasis, and is taken orally or by injection, usually three times a day. Amoxicillin treats infections like sinus infections, ear infections, and strep throat, and is available in various forms, including tablets, capsules, and liquid. Both medications are available in generic forms. Common side effects of metronidazole include nausea and a metallic taste, and it should not be taken with alcohol and can interact with warfarin. Amoxicillin can cause diarrhea and rash, and it may interact with medications like warfarin. Both medications require a prescription, but they have different dosing schedules and specific interactions to be aware of.

  • Metronidazole (Flagyl)
    Amoxicillin (Amoxil)
  • Metronidazole (Flagyl)
    Amoxicillin (Amoxil)

  • Summary of Metronidazole vs. Amoxicillin

    Summary for Nitroimidazole antibiotic
    Prescription only

    Metronidazole (Flagyl) is an oral antibiotic for adults and children. It's used to treat certain bacterial and parasitic infections, including bacterial vaginosis (a type of vaginal bacteria infection) and trichomoniasis (a sexually transmitted infection, or STI). Metronidazole (Flagyl) is taken by mouth, typically 3 times a day. Some common side effects of this medication include diarrhea, nausea, and vomiting. Avoid drinking alcohol while taking and for 3 days after stopping metronidazole (Flagyl) because this combination can cause a serious reaction. Metronidazole (Flagyl) is available as a lower-cost generic.

    Summary for Penicillin antibiotic
    Prescription only

    Amoxicillin (Amoxil) is a penicillin antibiotic that's used to treat a wide variety of bacterial infections, such as sinus infections, ear infections, strep throat, and urinary tract infections (UTIs). It's available as oral pills, a chewable tablet, and an oral liquid. Amoxicillin (Amoxil) is well-tolerated, but possible side effects include diarrhea, vomiting, and rash.

  • Indications of Metronidazole vs. Amoxicillin

    Indications for

    Treatment of certain bacterial and parasitic infections, including:

    •Trichomoniasis
    •Amebiasis (parasitic gut infection)
    •Serious bacterial infections, such as:
    •Abdominal infection (including peritonitis)
    •Skin infections
    •Gynecological infections (including endometritis)
    •Bloodstream infection (septicemia)
    •Bone and joint infections
    •Central nervous system infections (meningitis)
    •Lung infections (lower respiratory tract infections)
    •Heart infection (endocarditis)
    Indications for
    •Upper respiratory tract infections (ear, nose, and throat infections)
    •Lower respiratory tract infections (e.g., pneumonia, bronchitis)
    •Urinary tract infections (UTIs)
    •Skin infections (e.g., cellulitis)
    •Helicobacter pylori infection (adults only)

  • Pros and Cons of Metronidazole vs. Amoxicillin

    Pros and Const for Nitroimidazole antibiotic
    Pros
    •Taken by mouth
    •Available as a lower-cost generic medication
    •Can be used to treat different types of bacterial infection
    •Immediate-release formulations can be taken with or without food
    Cons
    •Immediate-release formulations needs to be taken multiple times a day for most infections
    •Serious interaction with alcohol
    •Can cause metallic taste in mouth
    •Not recommended while breastfeeding
    Pros and Const for Penicillin antibiotic
    Pros
    •Works well to treat many different bacterial infections
    •Can use for adults and children
    •Available in many forms (e.g., oral tablet, chewable tablet, capsule, liquid)
    •Liquid form comes in many different flavors to make it taste better
    Cons
    •Might need to take up to three times per day
    •Can cause stomach side effects like nausea, vomiting, and diarrhea
    •Not the best option if you have severe kidney problems
    •Might not be able to take this medication if you've had a severe allergy to penicillin

  • Common Side Effects of Metronidazole vs. Amoxicillin

    Common Side Effects for

    Please note: These are common side effects reported by people who took extended-release metronidazole (Flagyl)

    •Headache (18%)
    •Inflammation of the vagina (15%)
    •Nausea (10%)
    •Metallic taste (9%)
    •Flu-like symptoms (6%)
    Common Side Effects for
    •Diarrhea
    •Nausea
    •Vomiting
    •Rash

  • Warnings of Metronidazole vs. Amoxicillin

    Common Side Effects for
    •Possible risk of cancer
    •Serious allergic reactions
    •Brain and nerve problems
    •Liver and kidney problems
    •Risk of fungal infection
    •Risk of drug resistance
    •Lower white blood cell counts
    •Interaction with other medications
    Common Side Effects for
    •Severe allergic and skin reactions
    •Diarrhea from Clostridioides difficile infection
    •Development of drug-resistant bacteria

  • Prices with our coupons for Metronidazole vs. Amoxicillin

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    Learn more about Amoxicillin

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