Are there any interactions between ciprofloxacin (Cipro) and trimethoprim/sulfamethoxazole (Septra)?

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Last updated: May 14, 2025View editorial policy

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From the Guidelines

Ciprofloxacin and Septra (trimethoprim-sulfamethoxazole) should generally not be taken together unless specifically directed by a healthcare provider, as they can increase the risk of adverse effects such as kidney problems, tendon damage, and QT interval prolongation. The evidence from various studies, including those published in the British Journal of Dermatology 1 and Clinical Infectious Diseases 1, suggests that these antibiotics can have overlapping side effects and interact with each other in ways that may increase the risk of morbidity and mortality.

Some key points to consider when taking these medications together include:

  • Increased risk of kidney problems, particularly in patients with pre-existing renal impairment
  • Potential for tendon damage and QT interval prolongation, which can affect heart rhythm
  • Risk of hypoglycemia (low blood sugar) and other adverse effects
  • Importance of careful monitoring and medical guidance when taking these medications together

It is essential to inform your healthcare provider about all medications you are taking, including ciprofloxacin and Septra, to minimize the risk of adverse interactions. In some specific serious infections, doctors might intentionally prescribe both medications for synergistic effects, but this requires careful monitoring and medical guidance. Neither medication should be stopped without medical guidance, and patients should always take these medications exactly as prescribed and report any unusual symptoms to their healthcare provider immediately.

From the Research

Interactions between Ciprofloxacin and Septra

  • There are no direct studies on the interactions between ciprofloxacin and Septra (a combination of sulfamethoxazole and trimethoprim) in the provided evidence.
  • However, several studies have compared the efficacy and safety of ciprofloxacin and trimethoprim-sulfamethoxazole (the components of Septra) in the treatment and prevention of urinary tract infections 2, 3, 4.
  • These studies suggest that ciprofloxacin and trimethoprim-sulfamethoxazole have similar efficacy in treating urinary tract infections, but ciprofloxacin may be associated with fewer adverse reactions 3, 4.
  • One study found that the addition of a 30-day course of ciprofloxacin to sulfamethoxazole-trimethoprim prophylaxis lowered the incidence of urinary tract infections after kidney transplantation 5.
  • The available evidence does not provide information on potential interactions between ciprofloxacin and Septra, such as increased risk of adverse effects or reduced efficacy of either medication.
  • Further research is needed to fully understand the interactions between ciprofloxacin and Septra.

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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