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Updated on September 13, 2023
4 min read

What Happens When You Mix Metronidazole and Alcohol?

What is Metronidazole (Flagyl)?

Metronidazole, also known by its brand name Flagyl, is an FDA-approved antibiotic and antiprotozoal drug. It’s used to treat various bacterial infections, especially those that affect the:

  • Gastrointestinal system
  • Stomach or intestines
  • Respiratory tract
  • Skin
  • Brain
  • Heart
  • Liver
  • Vagina (bacterial vaginosis)

Metronidazole prescriptions typically come with a warning to avoid drinking alcohol while taking it. Metronidazole can interact with alcohol, causing unpleasant effects.


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What Happens When You Drink Alcohol While Taking Metronidazole?

Alcohol does not impact the therapeutic effectiveness of metronidazole. But metronidazole can affect how the body handles alcohol.

When the body metabolizes alcohol, it breaks it down into a toxic compound known as acetaldehyde. Your body then uses an enzyme to turn it into acetate.

However, metronidazole stops this enzyme from working, which stops the body from properly metabolizing the alcohol. This toxic build-up of acetaldehyde in the bloodstream causes unpleasant side effects like:

  • Reddening or flushing of the face
  • Headaches
  • Abdominal/stomach pain
  • Cramps
  • Nausea and vomiting
  • Discolored urine
  • Diarrhea

Risks of Mixing Metronidazole and Alcohol 

Mixing metronidazole and alcohol also causes a disulfiram-like reaction. Disulfiram treats chronic alcoholism and causes unpleasant side effects whenever you drink alcohol.

This disulfiram-like reaction can cause serious issues. Thankfully, the severe risks are rare and typically only happen if you take the medication for a long time.

These side effects include:

  • Nausea and vomiting
  • Headaches
  • Seizures
  • Encephalopathy
  • Chest pain
  • Rapid heartbeat
  • Low blood pressure
  • Numbness in the hands or feet

The disulfiram-like reaction can also cause serious skin reactions, such as DRESS syndrome. Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare and severe medication allergy.

How Long Does Metronidazole Treatment Take?

Metronidazole is typically prescribed for approximately 10 days. If you drink alcohol during treatment, you’ll be putting yourself at risk for potential side effects.

For most people, metronidazole may still be present in the body up to 40 hours after your last dose. However, it can stay in your body for up to 6 days if you have liver problems. 

Because of this, you should avoid alcohol during treatment and 3 days after the last dose. For topical metronidazole, you should avoid alcohol for 24 hours after the last application.

Can You Overdose on Metronidazole?

Yes, it is possible to take too much metronidazole and overdose. Symptoms of overdose include:

  • Nausea or vomiting
  • Loss of appetite
  • Headaches
  • Problems with muscle coordination
  • Pain, burning, tingling, or numbness in the hands or feet
  • Seizures
  • Diarrhea

If you or someone you know thinks they may have taken too much metronidazole, call your doctor or the American Association of Poison Control Centers (1-800-222-1222).

If symptoms are severe, call 911 or head to your nearest emergency room for immediate care.


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Who is At Risk When Mixing Metronidazole and Alcohol?

The interaction between metronidazole and alcohol isn’t well studied. However, certain people are at risk for the side effects of one substance or the other.

The people at risk for this interaction include:

  • People with liver problems: They can’t properly metabolize both substances, which can cause a toxic build-up
  • Pregnant women: Both metronidazole and alcohol may harm an unborn baby
  • Older adults: They are more sensitive to the effects of alcohol and are more prone to alcohol-related accidents

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What Other Drugs Interact With Metronidazole?

In addition to alcohol, metronidazole may interact with other prescription and over-the-counter medications and nutrition supplements. 

Tell your doctor about your health and medication history before taking metronidazole. Medications that may interact with metronidazole include:

  • Disulfiram
  • Warfarin
  • Lithium
  • Busulfan

Metronidazole boosts the efficiency of blood-thinning medications, increasing the risk for abnormal bleeding. Doctors often reduce the dose of a usual blood-thinning medication, such as warfarin, when combined with metronidazole.

Metronidazole can increase sensitivity to the sun. Limiting sun exposure by using sunscreen, wearing hats, and protective clothing is important.


Metronidazole is an antibiotic and antiprotozoal medication used to treat bacterial infections. Drinking alcohol while taking metronidazole results in unpleasant side effects that may range from mild to severe.

Mixing metronidazole and alcohol can create disulfiram-like effects. This reaction can potentially cause serious side effects.

If you want to drink alcohol, wait at least 3 days after your last dose, and 6 days if you have liver problems. If you experience severe side effects or overdose symptoms, seek medical attention.

Updated on September 13, 2023
8 sources cited
Updated on September 13, 2023
All Alcoholrehabhelp content is medically reviewed or fact checked to ensure as much factual accuracy as possible.

We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies.
  1. Can you drink alcohol with antibiotics?”, 2022.
  2. Metronidazole.” 
  3. Metronidazole: MedlinePlus Drug Information.” Medlineplus.Gov, 2019.
  4. Metronidazole (Oral Route) Description and Brand Names – Mayo Clinic.” Mayoclinic.Org, 2019.
  5. Alonzo et al. “Disulfiram-like Reaction With Metronidazole: An Unsuspected Culprit.” The journal of Pediatric Pharmacology and Therapeutics: JPPT: the Official Journal, 2019.
  6. Steel, B. & Wharton, C. “Metronidazole and alcohol.” Br Dent J, 2020.
  7. Mergenhagen et al. “Fact versus Fiction: a Review of the Evidence behind Alcohol and Antibiotic Interactions.” Antimicrobial Agents and Chemotherapy, 2020.
  8. Fjeld et al. “Er det virkelig farlig å kombinere metronidazol og alkohol? [Is combining metronidazole and alcohol really hazardous?].” Tidsskrift for den Norske laegeforening: tidsskrift for praktisk medicin, ny raekke, 2014.
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All content created by Alcohol Rehab Help is sourced from current scientific research and fact-checked by an addiction counseling expert. However, the information provided by Alcohol Rehab Help is not a substitute for professional treatment advice.
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