Can You Take Nitrofurantoin With Diflucan (Fluconazole) Together?

In our latest question and answer, the pharmacist discusses whether or not there is a drug interaction between nitrofurantoin and Diflucan (fluconazole).

Question

Can nitrofurantoin be taken at the same time as Diflucan?

Asked by Questions On Aug 29, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Aug 29, 2022
Last updated Apr 12, 2024

Key points

  • There have been rare case reports of the combination of fluconazole and nitrofurantoin causing liver and lung toxicity, but these are thought to be very rare.
  • Fluconazole and nitrofurantoin are generally considered safe to use together and are used in combination often.
  • Be sure to reach out to your doctor if you notice any side effects while taking this combination of medication..

Answer

Thanks for reaching out to us!

Overall, it is considered safe to use nitrofurantoin (Macrobid) and fluconazole (Diflucan) together. This combination makes sense to use in urinary infections that are thought to be of bacterial and/or fungal origin and these drugs are commonly used together safely.

However, it is important to note that there is at least one case report of these drugs causing liver toxicity and lung toxicity when used together. One such case report was detailed in a 2004 study published in the journal 'Annals of Pharmacotherapy'. The mechanism by which the interaction occurred is unclear and it's not known if there were other factors at play.

With chronic use, nitrofurantoin has been associated with lung toxicity and Diflucan with liver toxicity, but these problems are both quite rare. The case report published may have been very specific to the individual experiencing the issues.

Nevertheless, if both are used together, it would be prudent to monitor for signs of side effects (e.g. cough, significant fatigue, etc...) and let your doctor know if they occur.

Information About Nitrofurantoin

Nitrofurantoin is an antibiotic that is only approved for the treatment of urinary tract infections. This is because nitrofurantoin is quickly and extensively concentrated in the urine. It has been approved by the FDA since 1953.

The half-life of nitrofurantoin is only about 20 minutes and typically reaches peak urinary concentrations in about 30 minutes.

Because nitrofurantoin is excreted in the urine, the manufacturer does not recommend use in patients with impaired renal function (creatinine clearance below 60 mL/min). In addition, nitrofurantoin is listed by the Beers Criteria as a medication to avoid in elderly adults with a creatinine clearance of less than 30 mL/minute.

Information About Fluconazole

Fluconazole is an antifungal that can be used for a wide range of fungal infections. It has been approved by the FDA since January of 1990. In 1994, the FDA approved a single dose for the treatment of uncomplicated vulvovaginal candidiasis (yeast infection).

 The half-life for Diflucan usually ranges between 20 and 50 hours (approximately 30 hours in most patients). Fluconazole is well absorbed via the oral route with a bioavailability of 90%. Peak concentration takes place in 1 to 2 hours with both oral and intravenous routes.

Fluconazole has been rarely associated with QT prolongation. This would be of concern in patients with proarrhythmic conditions or when taking other medications that prolong the QT interval. Nitrofurantoin has not been associated with an increased QT.

Final Words

Thanks again for your question and feel free to reach back out anytime!


References

  • Pulmonary and hepatic toxicity due to nitrofurantoin and fluconazole treatment, PubMed
  • Nitrofurantoin Monograph, PubChem
  • Fluconazole Monograph, PubChem

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at [email protected]! You can also connect with Dr. Brian Staiger on LinkedIn.

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