Can Metronidazole Change Urine Color?

In our latest question and answer, the pharmacist discusses whether or not metronidazole (Flagyl) can change the color of your urine.


Can metronidazole change your urine color? Mine is a darker color than usual.

Asked by Sammy On Aug 23, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Aug 23, 2022
Last updated Apr 20, 2024

Key points

  • A common side effect of Flagyl (metronidazole) is a change in urine color.


Flagyl (metronidazole) is both an antibacterial as well as an antiprotozoal agent. One of the most common side effects of metronidazole is urine discoloration, which commonly manifests as a darker than usual color.

Metronidazole is commonly prescribed to treat many types of skin infections, lower respiratory tract infections, and vaginal infections. Because metronidazole is effective against a variety of pathogens, it is widely used both as monotherapy (i.e. alone) as well as in combination with other medications.

Metronidazole Side Effects

Common side effects of metronidazole include but are not limited to:

  • Urine discoloration/dark urine
  • Headache
  • Diarrhea
  • Metallic taste
  • Nausea
  • Upset stomach

Metronidazole can be taken with or without food but should never be taken with any type of ethanol (including alcoholic beverages and common cough medications). If ethanol-containing substances are ingested while taking metronidazole, side effects can be severe and include:

  • Vomiting
  • Nausea
  • Headache
  • Rapid heart rate
  • Flushing
  • Abdominal cramps

Ethanol-containing products should not be ingested for up to three days after completing a course of metronidazole to avoid these effects. 

Final Words

Thanks again for your question!

Metronidazole is cleared fairly quickly from your system, so if you have noticed a change in urine color due to the medication, it should go back to its usual color within a day or two at the latest.


  • Flagyl Prescribing Information, Pfizer

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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