Which antibiotics work best for UTIs?

Written by Brendan Levy

Should I be taking Macrobid (nitrofurantoin), Bactrim, Monurol, Keflex, Cipro or what?

What type of urinary tract infection (UTI) are we talking about?

When doctors say UTI they can mean any infection of the urinary tract (bladder, urethra, ureters, kidneys, etc). However commonly they mean simple uncomplicated acute cystitis in a young woman - here's what each of those parts means:

  • Simple and uncomplicated implies that the woman is not pregnant, diabetic, immune compromise, had recent bladder surgery - or anything else that might make the situation trickier.
  • Acute means it's an infection that just started and has lasted less than about 10 days - not something that's been going on for weeks or months.
  • Cystitis means it's an infection of the bladder and not the kidneys or other more serious urinary tract infection types.
  • Young this usually means someone under 65 or so - older patients can get UTIs that are different and sometimes don't even cause pain but that can cause symptoms like delirium or confusion.
  • Woman since men have a much lower risk of UTI generally because of their longer urethra when they do get one it requires different testing and treatment than what we usually mean when we talk about UTI.

Okay - so how do you treat a UTI (acute uncomplicated cystitis)?

There are a few antibiotics we usually use to start. We choose them because they tend to have a lower risk of side effects and because they are effective at killing the bacteria and helping to cure the UTI. Overall we always think about a risk and benefit ratio (i.e. what is the benefit you get and how big is the risk you take for that benefit). Here are some of the most commonly prescribe antibiotics:

  • Macrobid (nitrofurantoin) is now one of the most recommended antibiotics because it has fewew serious side effects, doesn't disturb your good bacteria as much, and it can kill most UTI bacteria. It is considered relatively pregnancy safe in the second and third trimesters.
  • Bactrim (trimethoprim-sulfamethoxazole) is a Sulfa antibiotic and is also extremely commonly used.
  • Cipro (ciprofloxaxin) was, until recently, the most popular antibiotic for UTI treatment. It is still a good choice, but more bacteria are resistant to it and doctors have learned more about serious side effects including heart problems and tendon rupture - so it's usually not first choice anymore. It does get into the kidneys better than some other antibiotics though - so is still often used in home treatment of kidney infections.
  • Keflex (cephalexin) is a cephalosporin antibiotic that is increasingly used for UTIs especially where there is any concern for a kidney infection. It is partly replacing ciprofloxacin in that role.
  • Monurol (fosfomycyin) is a powder that you mix and usually just requires one dose. It is a great option and can be used by people who can't swallow pills, but unfortunately many pharmacies don't carry it.

Talk to your doctor about what antibiotic is best for you if you have a UTI. Even if you used a certain medicine in the past - changing bacterial resistance patterns, and changes in our understanding of each drug - may cause them to recommend something new.

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