Drinking alcohol while taking Flagyl can cause serious side effects. Doctors and pharmacists advise people to avoid alcohol completely while using the drug in any form, including Flagyl oral tablets and topical Flagyl creams.
Flagyl is an antibiotic that treats many infections, including abdominal infections. While not all antibiotics interact with alcohol, drinking while using certain types, including Flagyl, can have serious health consequences. People should generally avoid alcohol for up to 3 days after the last dose of Flagyl.
What is Flagyl?
Flagyl is the brand name for the antibiotic metronidazole. Metronidazole is part of the family of antibiotics called nitroimidazoles. Doctors use Flagyl to treat infections related to anaerobic bacteria. Flagyl can treat and prevent the following:
- Abdominal infections
- Skin infections
- Bone and joint infections.
- Central nervous system infections.
- Respiratory infections.
- Infections of the lining of the heart.
The drug is also available as a cream, gel, and lotion to treat rosacea.
Possible effects of mixing Flagyl and alcohol
Some antibiotics are safe to consume with an occasional drink, but Flagyl and alcohol interact in a number of ways. Taking Flagyl and drinking alcohol can have similar effects, which can be more noticeable when a person combines the two. People may experience the following side effects from Flagyl:
- Abdominal cramps.
Alcohol can make stomach and digestion-related side effects more pronounced. While some people do not experience the effects of combining alcohol and Flagyl, doctors and pharmacists recommend avoiding alcohol as a precaution. This can reduce the risk of Flagyl causing side effects.
Alcohol can also lower a person’s seizure threshold. Since Flagyl can cause seizures, people with a history of seizures should be especially careful to avoid alcohol while taking the antibiotic.
How do Flagyl and alcohol interact?
When a person consumes alcohol, the body breaks it down in two steps. First, it breaks the alcohol down into a compound called acetaldehyde. Acetaldehyde is toxic and is responsible for the unwanted effects of alcohol. The body then reduces the acetaldehyde to acetate. It does this with an enzyme called aldehyde dehydrogenase. Flagyl blocks the effects of this enzyme. As a result, a person on Flagyl cannot fully digest alcohol, and drinking can cause toxic acetaldehyde to build up in the bloodstream. Because of this, people who drink alcohol while taking Flagyl may experience a reaction similar to disulfiram.
The disulfiram reaction
Disulfiram is a drug that helps treat alcohol addiction. The mixture of disulfiram and alcohol has health effects that discourage people from drinking. A disulfiram-like reaction occurs when alcohol interacts in a similar way with a non-disulfiram drug, such as Flagyl. When a person combines Flagyl and alcohol, their disulfiram-like reaction can be mild to moderate and include:
- A racing heartbeat.
- Low blood pressure.
- Redness of the face.
The authors of a 1996 case study reported the death of a 31-year-old woman who consumed alcohol while taking metronidazole. Reactions do not happen in everyone. This may suggest that the risk of developing a disulfiram-type reaction to Flagyl and alcohol varies from person to person. Since doctors cannot determine the risk of an individual reaction, everyone should avoid drinking alcohol while taking Flagyl.
Rich in creams, gels, and lotions based on metronidazole cannot rule out the possibility of reactions similar to disulfiram. Doctors and pharmacists should remind people using topical metronidazole products to avoid alcohol.
When is it safe to drink alcohol again?
Interactions between alcohol and Flagyl, specifically the inhibition of Flagyl aldehyde dehydrogenase, can continue for up to 3 days after a person stops taking the antibiotic. As a result, doctors and pharmacists generally recommend avoiding alcohol while taking Flagyl and for 3 days after the last dose due to the risk of side effects. For people applying metronidazole products to the skin or using the vaginal gel, the manufacturers recommend avoiding alcohol for up to 24 hours after the last application.
How to use Flagyl safely
Flagyl can accumulate in the bloodstream of a person with liver failure, and doctors prescribe lower doses for people with severe liver disease. People with kidney failure are at similar risk, and doctors will watch carefully for signs of build-up.
The drug can also accumulate in people older than 70 years who do not have signs of liver or kidney failure. Doctors will prescribe the regular dose for older adults, but will monitor them closely for side effects.
Doctors and pharmacists should advise everyone taking Flagyl to avoid alcohol while taking the drug and for 3 days after the final dose. People who apply the antibiotic topically should avoid alcohol during treatment and for 24 hours after the last application.