What is the interaction between metronidazole (Flagyl) and alcohol (ethanol) consumption, specifically with beer?

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Last updated: April 27, 2025View editorial policy

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From the Guidelines

Patients taking metronidazole should avoid consuming beer and other alcohol-containing products during treatment and for at least 24 hours thereafter. This recommendation is based on the potential for a disulfiram-like reaction, which can cause unpleasant and potentially dangerous symptoms such as facial flushing, headache, nausea, vomiting, abdominal cramps, and rapid heart rate 1. The severity of the reaction varies between individuals, but it can be quite severe and distressing. Even small amounts of alcohol found in foods, mouthwashes, or cough syrups may trigger this reaction in some people.

Some key points to consider:

  • Metronidazole inhibits the enzyme aldehyde dehydrogenase, which is responsible for breaking down acetaldehyde, a toxic byproduct of alcohol metabolism.
  • When this enzyme is blocked, acetaldehyde accumulates in the bloodstream, causing unpleasant and potentially dangerous symptoms.
  • The recommended period of abstinence from alcohol is at least 24 hours after completing treatment with metronidazole, as stated in the 1993 guidelines from the Centers for Disease Control and Prevention 1.
  • It is essential to read medication labels carefully and avoid all alcohol-containing products during treatment and for the recommended period afterward.

Other studies, such as those related to diabetes and cancer prevention, provide general guidelines for alcohol consumption but do not specifically address the interaction between metronidazole and alcohol 1. However, these studies do emphasize the importance of moderate alcohol consumption and the potential risks associated with excessive drinking. In the context of metronidazole treatment, it is crucial to prioritize the guidelines provided by the Centers for Disease Control and Prevention to minimize the risk of adverse reactions.

From the FDA Drug Label

Alcoholic beverages should be avoided while taking metronidazole tablets and for at least one day afterward. If patients receiving metronidazole drink alcoholic beverages, they may experience abdominal distress, nausea, vomiting, flushing, or headache. Interaction between metronidazole and beer: Patients should avoid consuming beer (an alcoholic beverage) while taking metronidazole and for at least one day afterward, as it may cause abdominal distress, nausea, vomiting, flushing, or headache 2, 2.

From the Research

Interaction of Metronidazole and Beer

  • The interaction between metronidazole and beer is primarily related to the disulfiram-like reaction that can occur when metronidazole is taken with alcohol 3, 4.
  • This reaction can cause symptoms such as nausea, vomiting, and flushing, and is similar to the reaction that occurs when disulfiram is taken with alcohol.
  • The exact mechanism of this reaction is not fully understood, but it is thought to be related to the inhibition of aldehyde dehydrogenase, an enzyme that is involved in the metabolism of alcohol 5.
  • It is recommended that patients taking metronidazole avoid consuming alcohol, including beer, to minimize the risk of this reaction 6, 7.
  • The severity of the reaction can vary depending on the amount of alcohol consumed and the individual's sensitivity to the reaction.
  • In general, it is advised to avoid consuming alcohol while taking metronidazole and for at least 24 hours after finishing the course of treatment to minimize the risk of this reaction.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Metronidazole.

Annals of internal medicine, 1980

Research

[Metronidazole].

Annales de dermatologie et de venereologie, 2001

Research

Therapeutic uses of metronidazole and its side effects: an update.

European review for medical and pharmacological sciences, 2019

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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