From the Guidelines
You should not consume alcohol while taking Flagyl (metronidazole) or for at least 24 hours after completing the medication. Combining alcohol with metronidazole causes a disulfiram-like reaction, which can be very unpleasant and potentially dangerous, leading to increased morbidity and mortality, and decreased quality of life 1. When metronidazole and alcohol interact in your body, the medication blocks the complete breakdown of alcohol, causing a buildup of acetaldehyde in your bloodstream. This leads to symptoms such as severe nausea, vomiting, headache, flushing, abdominal cramps, rapid heart rate, and low blood pressure. The reaction can begin within 30 minutes of alcohol consumption and may last several hours. Even small amounts of alcohol should be avoided, including alcohol-containing products like certain mouthwashes, cough syrups, and some food preparations. Some key points to consider include:
- The importance of avoiding alcohol during metronidazole treatment to prevent adverse reactions
- The potential for increased morbidity and mortality if alcohol is consumed during treatment
- The need to advise patients to abstain from alcohol for at least 24 hours after completing the medication, as recommended by the Centers for Disease Control and Prevention in their 1993 guidelines 1.
From the FDA Drug Label
Alcoholic beverages should be avoided while taking metronidazole tablets and for at least one day afterward. Alcoholic beverages should not be consumed during metronidazole therapy and for at least one day afterward because abdominal cramps, nausea, vomiting, headaches, and flushing may occur If patients receiving metronidazole drink alcoholic beverages, they may experience abdominal distress, nausea, vomiting, flushing, or headache.
Reason for avoidance: The combination of metronidazole and alcohol may cause adverse reactions such as:
- Abdominal cramps
- Nausea
- Vomiting
- Headaches
- Flushing It is recommended to avoid alcohol consumption during metronidazole therapy and for at least one day afterward to minimize the risk of these adverse reactions 2, 2, 2.
From the Research
Mechanism of Disulfiram-Like Reaction
- The disulfiram-like reaction is typically associated with the inhibition of hepatic aldehyde dehydrogenase, leading to the accumulation of acetaldehyde in the blood 3.
- However, metronidazole does not inhibit hepatic aldehyde dehydrogenase, and its mechanism of action is thought to be related to the alteration of gut flora 4, 3.
Effect of Metronidazole on Acetaldehyde Levels
- Metronidazole has been shown to increase intracolonic acetaldehyde levels in rats receiving ethanol, but not peripheral blood acetaldehyde levels 4.
- In human studies, metronidazole did not increase blood acetaldehyde levels when co-administered with ethanol 5, 6.
Clinical Evidence
- A case-control study found no significant difference in disulfiram-like effects between patients receiving metronidazole and ethanol, and those receiving ethanol alone 6.
- Another study found that metronidazole did not have any objective or subjective disulfiram-like properties when co-administered with ethanol in healthy male volunteers 5.
Conclusion is not allowed, so the response will continue with more information
Interaction between Metronidazole and Ethanol
- The interaction between metronidazole and ethanol is thought to be related to the alteration of gut flora, rather than the inhibition of hepatic aldehyde dehydrogenase 4, 3.
- Metronidazole has been shown to increase the growth of Enterobacteriaceae in the gut, which may contribute to the increase in intracolonic acetaldehyde levels 4.