What foods affect metronidazole?

October 8, 2025 •

3 min read

In some studies, metronidazole is one of the most commonly prescribed antibiotics, accounting for over 11% of antibiotic prescriptions. When taking this medication, it is crucial to know what foods affect metronidazole to avoid potentially serious reactions.

Quick Summary

While taking metronidazole, you must avoid all forms of alcohol and products containing propylene glycol. This restriction extends for at least three days after your last dose to prevent severe side effects.

Key Points

Alcohol Abstinence is Crucial: You must not consume any alcohol while taking metronidazole and for at least 3 days after your last dose to prevent a severe reaction.
Watch for Propylene Glycol: This common food additive, found in soft drinks and baked goods, can cause the same reaction as alcohol and must be avoided.
Read All Labels: Hidden alcohol and propylene glycol can be found in mouthwash, cough syrups, salad dressings, and various processed foods.
Disulfiram-Like Reaction: Mixing metronidazole with alcohol or propylene glycol can cause severe nausea, vomiting, flushing, and heart palpitations.
Take With Food for Comfort: While not required, taking metronidazole with food or crackers can help minimize common side effects like stomach upset and nausea.
No Other Major Food Interactions: Aside from alcohol and propylene glycol, there are no other major, clinically significant food interactions to worry about.
Finish The Full Course: It is important to complete the entire prescribed course of metronidazole, even if you start feeling better, to prevent the infection from returning.

Metronidazole is an antibiotic and antiprotozoal medication used to treat a wide variety of infections, from bacterial vaginosis and H. pylori to parasitic infections like giardia. While effective, its interaction with certain substances is a critical safety concern. Patients must be aware of which foods and ingredients to avoid to prevent unpleasant and potentially dangerous side effects.

The Primary Interaction: Alcohol

The most significant interaction with metronidazole is alcohol. Consuming alcohol during treatment can cause a "disulfiram-like reaction". Metronidazole may interfere with how your body processes alcohol, leading to a build-up of a toxic compound called acetaldehyde, which causes symptoms.

Symptoms of this reaction can include severe nausea, vomiting, stomach cramps, headaches, flushing, and a fast heartbeat. These symptoms can occur with even small amounts of alcohol. Healthcare professionals strongly advise avoiding all alcohol during treatment and for at least three days after the last dose to allow the medication to clear from your system.

Hidden Sources of Alcohol

Alcohol can be found in places other than beverages. Always check labels for alcohol content in:

Liquid medications: Some cough syrups and cold remedies.
Food products: Certain vinegars, sauces, marinades, and desserts.
Flavor extracts: Vanilla, almond, and other extracts.
Mouthwash: Many types contain alcohol.

The Secondary Interaction: Propylene Glycol

Propylene glycol, a synthetic food additive, should also be avoided. It is used in many products to maintain moisture and act as a solvent. Mixing propylene glycol with metronidazole can trigger the same disulfiram-like reaction as alcohol.

Where to Find Propylene Glycol

Propylene glycol is in numerous processed foods. Check labels for this ingredient in:

Packaged Baked Goods: Cake mixes and cookies.
Desserts: Ice cream and frozen yogurt.
Beverages: Soft drinks and flavored coffees.
Condiments: Salad dressings and barbecue sauces.
Fast Food and Packaged Meals: Various prepared items.


Substance to Avoid	Why Avoid It	How Long to Avoid	Common Sources
Alcohol (Ethanol)	Can cause a severe disulfiram-like reaction.	During treatment and for at least 3 days after the last dose.	Beer, wine, liquor, mouthwash, some cough syrups, certain sauces and vinegars.
Propylene Glycol	Can cause the same disulfiram-like reaction as alcohol.	During treatment and for at least 3 days after the last dose.	Soft drinks, cake mixes, salad dressings, ice cream, fast food, food colorings, flavorings.

Other Considerations

Metronidazole can usually be taken with or without food. However, taking it with a meal or a bland snack might help reduce common side effects like nausea or an upset stomach. The extended-release version should be taken on an empty stomach. There are no other major, clinically significant food interactions like those with tyramine-rich foods that some sources mention.

Conclusion

To safely take metronidazole, it is essential to completely avoid alcohol and products containing propylene glycol throughout the treatment and for at least three days afterward. Always check ingredient labels for both obvious and hidden sources of these substances. Taking the medication with food can help if you experience a metallic taste or stomach upset. Consult your healthcare provider if you have any concerns.

Mayo Clinic - Metronidazole (Oral Route)

Frequently Asked Questions

You may experience a disulfiram-like reaction, which can include severe nausea, vomiting, stomach cramps, headache, and skin flushing. Symptoms can last from 30 minutes to several hours. If you have a severe reaction, seek medical advice.

You should wait for at least three days (72 hours) after your last dose before consuming any alcohol or products containing propylene glycol. This allows enough time for the medication to be cleared from your system.

No, you should avoid mouthwash containing alcohol. The alcohol can be absorbed and potentially cause the same negative reaction as drinking an alcoholic beverage.

Propylene glycol is a food additive found in many processed foods like soft drinks, cake mixes, salad dressings, and ice cream. It can cause a reaction similar to alcohol when mixed with metronidazole, so you must read labels and avoid it.

Standard metronidazole tablets can be taken with or without food. Taking them with food may help reduce stomach upset. However, the extended-release version should be taken on an empty stomach, one hour before or two hours after a meal.

There are no known major interactions between grapefruit juice and metronidazole. The primary substances to avoid are alcohol and propylene glycol.

An unpleasant or sharp metallic taste is a common and known side effect of metronidazole. This taste usually goes away after you complete your treatment.