Does Nitrofurantoin (Nitrofur) cause diarrhea?

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Last updated: May 16, 2025View editorial policy

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From the Guidelines

Nitrofurantoin does not typically cause diarrhea as its main side effect, though it can occasionally affect bowel movements. This antibiotic is primarily used to treat urinary tract infections and works by killing bacteria in the urinary system. While gastrointestinal side effects can occur, they more commonly include nausea, vomiting, or loss of appetite rather than increased bowel movements. If you're taking nitrofurantoin and experiencing significant changes in bowel habits, this could be due to the medication's effect on gut bacteria, as antibiotics can disrupt the normal balance of microorganisms in your digestive system 1. Some key points to consider when taking nitrofurantoin include:

  • Taking the medication with food to reduce stomach upset
  • Completing the full prescribed course, typically 5-7 days for uncomplicated UTIs
  • Being aware of the potential for adverse events, such as pulmonary and hepatic toxicity, although these are extremely rare 1. It's also important to note that the American College of Physicians recommends prescribing short-course antibiotics, including nitrofurantoin, for the treatment of uncomplicated bacterial cystitis 1. If you experience severe diarrhea, especially with blood or mucus, contact your healthcare provider as this could indicate a more serious reaction requiring medical attention.

From the FDA Drug Label

Gastrointestinal: Nausea, emesis, and anorexia occur most often. Abdominal pain and diarrhea are less common gastrointestinal reactions. The FDA drug label mentions that diarrhea is a possible adverse reaction to Nitrofurantoin, which can be related to bowel movements or pooping. However, it does not explicitly state that Nitrofurantoin causes frequent bowel movements or pooping. 2 Key points:

  • Diarrhea is a possible adverse reaction
  • Abdominal pain is also a possible adverse reaction
  • The label does not explicitly mention an increase in bowel movements or pooping as an adverse reaction.

From the Research

Nitrofurantoin and Gastrointestinal Effects

  • Nitrofurantoin is commonly prescribed to treat urinary tract infections (UTI) and has been reported to have gastrointestinal side effects 3.
  • The most commonly reported side effects of nitrofurantoin include gastrointestinal and central nervous system symptoms 4.
  • However, there is no direct evidence in the provided studies that suggests nitrofurantoin causes diarrhea or makes you poop.

Comparison with Other Antibiotics

  • Other antibiotics such as trimethoprim-sulfamethoxazole, ciprofloxacin, and fosfomycin tromethamine have been compared to nitrofurantoin in terms of efficacy and side effects 4, 5.
  • These studies suggest that nitrofurantoin is at least comparable to other common UTI treatments in terms of clinical and bacteriological cure, but may have fewer side effects 4.

Treatment of Traveler's Diarrhea

  • The provided studies discuss the treatment of traveler's diarrhea with various antibiotics, including trimethoprim-sulfamethoxazole, ciprofloxacin, and rifaximin 6, 7, 5.
  • However, nitrofurantoin is not mentioned as a treatment option for traveler's diarrhea in these studies.

Conclusion on Nitrofurantoin and Diarrhea

  • Based on the provided evidence, there is no clear answer to whether nitrofurantoin makes you poop or causes diarrhea 3, 4.
  • Further research is needed to fully understand the gastrointestinal effects of nitrofurantoin and its comparison to other antibiotics.

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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