Compare Flagyl vs. Bactrim

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

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Treats and prevents bacterial infections.

Flagyl (metronidazole) is very good at treating certain bacterial infections, but you can't have any alcohol while on it since it'll make you throw up a lot.

Kills bacteria.

Bactrim (sulfamethoxazole / trimethoprim) is good for treating many bacterial infections and is available as a generic. However, you can be more likely to sunburn.

3.6/ 5 average rating with 473 reviewsforBactrim
Upsides
  • Flagyl (metronidazole) is good at killing a variety of bacteria.
  • Unlike many other antibiotics, Flagyl (metronidazole) is less likely to make bacteria resistant to it.
  • Most forms are available as a generic, so it's relatively cheap.
  • Widely available as a generic product and in a variety of formulations (tablet, capsule, suspension).
  • Works well to treat many types of bacterial infections
Downsides
  • You can't drink alcohol while on Flagyl (metronidazole), and for at least 3 days after you finish it.
  • Side effects can include nausea, headache, stomach upset, and a metallic taste in your mouth.
  • If you're taking Flagyl (metronidazole) for a long time, there's a risk of more side effects, such as nerve damage.
  • If you're on blood thinners, let your doctor know. Flagyl (metronidazole) can interact with your medicines and make you more likely to bleed.
  • Makes you sensitive to the sun.
  • Can upset your stomach
  • Drink plenty of water or fluids to avoid harming your kidneys
  • May cause birth defects
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Used for
Dosage forms
  • Pill
  • Extended-release pill
  • Injection
  • Pill
  • Liquid
Price
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Reviews
Not enough review data.Leave a review
473 reviews so far
59%
saidit'sworth it
49%
saiditworked well
22%
saidit'sa big hassle

Have you used Bactrim (sulfamethoxazole / trimethoprim)?

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Side effects
13possible side effects
  • Headache
    18%
  • Nausea
    10%
  • Metallic taste
    9%
  • Genital itching
    5%
  • Dizziness
    4%
  • Diarrhea
    4%
  • Stomach problems
    4%
  • Overgrowth of yeast
    3%
  • Stuffy nose
    3%
  • Menstrual cramps
    3%
  • Abnormal urine
    3%
  • Dry mouth
    2%
  • Urinary tract infection
    2%
See more detailed side effects
The Bactrim (sulfamethoxazole / trimethoprim) FDA package insert doesn’t have numbers about how common side effects are.
Risks and risk factors
  • Seizure or brain problems
    • Taking high doses of Flagyl (metronidazole)
    • Taking Flagyl (metronidazole) for a long time
  • Nerve damage
    • Taking high doses of Flagyl (metronidazole)
    • Taking Flagyl (metronidazole) for a long time
  • Cancer
  • New infection while taking Flagyl (metronidazole)
    • Taking Flagyl (metronidazole) incorrectly
  • Interaction with alcohol
    • Drinking alcohol while taking Flagyl (metronidazole)
See more detailed risks and warnings
  • Diarrhea
  • Sunburn
  • Rash
  • Harm to fetus
  • Lower kidney function
    • Elderly
    • Taking other medicines that lower kidney function
See more detailed risks and warnings