Is it safe to consume alcohol 48 hours after taking metronidazole (Flagyl)?

From the Guidelines

It is generally considered safe to drink alcohol 48 hours after taking your last dose of metronidazole. Metronidazole can cause a disulfiram-like reaction when combined with alcohol, leading to symptoms such as nausea, vomiting, flushing, headache, and abdominal cramps. The drug typically has a half-life of 6-8 hours and is substantially cleared from your system within 24-48 hours after the last dose. According to the Centers for Disease Control and Prevention guidelines from 2002 1, patients should be advised to avoid consuming alcohol during treatment with metronidazole and for 24 hours thereafter. However, a more recent study from 2021 1 suggests that patients should avoid alcohol for the therapeutic duration due to a disulfuram-like reaction, but it does not specify the exact duration after treatment. To be cautious, waiting a full 48 hours provides adequate time for the medication to be eliminated from your body, minimizing the risk of an adverse reaction. This recommendation applies to the standard oral formulations of metronidazole; if you were using a topical form, the risk of interaction is much lower. If you experience any unusual symptoms when resuming alcohol consumption, stop drinking and consult your healthcare provider. Remember that alcohol may also interfere with your recovery from the condition that required metronidazole treatment in the first place.

Some key points to consider:

• Metronidazole has a disulfiram-like reaction with alcohol, which can cause unpleasant symptoms
• The drug is substantially cleared from the system within 24-48 hours after the last dose
• Patients should avoid alcohol during treatment and for a certain period after, but the exact duration is not clearly specified in recent guidelines
• Waiting 48 hours after the last dose is a cautious approach to minimize the risk of an adverse reaction
• Alcohol may also interfere with recovery from the underlying condition being treated with metronidazole.

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 It is not ok to drink alcohol 48 hours after taking metronidazole, as the label only specifies to avoid alcohol for at least one day after taking the medication, and 48 hours is more than one day, but the label does not provide information for 48 hours. 2 2

From the Research

Interaction between Metronidazole and Alcohol

• The interaction between metronidazole and alcohol has been a topic of discussion, with some studies suggesting a disulfiram-like reaction 3, 4.
• However, recent research does not confirm a clinically relevant interaction between ethanol and metronidazole 3, 5.
• A study found that metronidazole does not increase acetaldehyde and cannot reliably produce disulfiram-like reactions 5.
• Another study suggested that the mechanism behind metronidazole-related disulfiram-like reaction might be located in the gut flora instead of the liver 4.

Safety of Drinking Alcohol after Taking Metronidazole

• There is no conclusive evidence to suggest that drinking alcohol 48 hours after taking metronidazole is hazardous 3, 5.
• A case-control study found no significant difference in disulfiram-like effects between patients who received metronidazole and those who did not, despite having similar ethanol concentrations 5.
• The study suggests that the clinical effects of a disulfiram-like reaction may be present at baseline from ethanol ingestion or underlying disease, regardless of metronidazole use 5.

General Guidelines for Alcohol Consumption

• Light and moderate alcohol consumption (up to 14 g per day for women and up to 28 g per day for men) may be associated with reduced mortality risk 6.
• Chronic heavy alcohol consumption and alcohol abuse can lead to alcohol-use disorder, resulting in physical and mental diseases 6.
• The safety of alcohol consumption depends on various factors, including population, dose, and context of consumption, as well as the endpoint of interest 7.