The Dangers of Flagyl and Alcohol

Warnings not to drink alcohol while taking a medication are often ignored. But mixing Flagyl (metronidazole), an antibiotic, with alcoholic beverages can make a person very sick. Find out what happens when these two drugs are mixed.

Flagyl (Metronidazole) Interactions With Alcohol

Flagyl is the brand name of metronidazole, an antibiotic used to treat a variety of infections, from stomach ulcers to meningitis. (Metronidazole is also found in some other brand name antibiotics, including ; check your antibiotic’s label.) Most of Flagyl’s side effects are run-of-the-mill, such as nausea and vomiting. However, Flagyl is reported to interact dangerously with another common drug: alcohol.

Drinking even a small amount of alcohol (ethanol) while taking Flagyl can make a person very sick. Flagyl and alcohol together cause severe nausea and vomiting, flushing, fast heartbeat (tachycardia), and shortness of breath. The reaction has been described as being similar to the effects of Antabuse, a drug that treats alcoholism by causing patients to become very sick when they drink.

Obviously, beverages containing alcohol should not be consumed during treatment with Flagyl, but small amounts of alcohol can be found in hidden sources as well. Some kinds of mouthwash and cold medicine contain alcohol. Small amounts may also be served at religious services. Patients should avoid all of these alcohol sources while taking Flagyl and for 48 hours following the end of treatment.

What Causes the Bad Reaction?

Because the Flagyl-alcohol reaction is said to resemble the Antabuse-alcohol reaction, researchers originally assumed that they work the same way. Ordinarily, the liver breaks down ethanol in two steps: first into acetaldehyde, then into acetic acid. Antabuse inhibits the second step, causing levels of acetaldehyde in the blood to rise. The increased blood acetaldehyde causes the acute symptoms of vomiting, flushing, etc.

More recent research has shown that Flagyl does not inhibit the breakdown of acetaldehyde, and that blood acetaldehyde does not increase when Flagyl and alcohol are combined. Therefore, some other mechanism must be at work. One set of researchers (Karamanakos et al. 2007) suggested it may be related to increased serotonin because they were able to show that Flagyl increases brain serotonin in rats. Another set of researchers (Visapää et al. 2002) noted that there are only 10 human case reports of a bad Flagyl-alcohol reaction and suggested that the problem may not be as common as previously thought. They did, however, note that it is possible that this “reaction can.

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3 thoughts on “The Dangers of Flagyl and Alcohol

    • Author gravatar

      I have had several bottles of wine since taking both flagyl and amoxicillin in preparation for dental surgery, in addition to my anti-depressants. I am completely fine. I am able to drive, go to work, and do my assignments for my doctoral program. I have not felt sick once, and it’s been a week.

    • Author gravatar

      The flagyl and alcohol warnings are BS. Notice that the side effects from the “combination” is the same as flagyl alone or alcohol alone. What I’ve read is that any “side effects” could have been from the flagyl OR the alcohol. Drink lightly just in case you do have a bad reaction to the flagyl alone. No need to double the bad effects with too much alcohol, too.

    • Author gravatar

      Oh my goodness, the interaction is real, and it is absolutely tied to alcohol consumption. Ive had to take Flagyl on several occasions throughout my life, and Ive messed up a few times while taking it, those moments when I’ve been on autopilot, drinking because I always drink in that setting. A glass of champagne at a bridal shower, a sip of communion wine, a beer after sailing. Every time, within two hours, I have felt violently ill. Not a casual, this might be a stomach bug illness, but rapid onset nausea that hangs out for a few hours. Then it’s gone. Everyone’s biology is different, so I’m sure plenty of people get away without the noticeable symptoms, but for me, no amount of good time is worth the misery that follows. I’ll take the glass of water, thank you.

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