Metronidazole (Flagyl) can interact with alcohol and other medications. For example, metronidazole can interact with sertraline (Zoloft) and warfarin (Jantoven).
Metronidazole is used for treating several bacterial and parasitic infections in adults. It’s also used to treat amebiasis (a parasitic infection) in children.
An interaction can occur because one substance causes another substance to have a different effect than expected. Interactions can also occur if you have certain health conditions.
This article will focus on interactions for generic metronidazole oral capsule and oral tablet. Metronidazole oral capsule is also available as the brand-name drug Flagyl. The oral tablet is not available in a brand-name version.
Metronidazole comes in other oral, topical, and injectable forms that may have different interactions. You can talk with your doctor to learn more about the interactions of the drug’s other forms.
Keep reading to learn about metronidazole’s possible interactions. For a detailed overview, check out this in-depth metronidazole article.
Before you start taking metronidazole, tell your doctor and pharmacist about any prescription, over-the-counter (OTC), or other drugs you take. Sharing this information with them may help prevent possible interactions. (To learn whether metronidazole interacts with herbs, vitamins, or supplements, see the “Are there other interactions with metronidazole?” section.)
If you have questions about drug interactions that may affect you, talk with your doctor or pharmacist. They can tell you more about what drugs should not be taken with metronidazole.
The following table lists drugs that may interact with metronidazole. Keep in mind that this table does not include all drugs that may interact with metronidazole. For more information about some of these interactions, see the “Drug interactions explained” section.
| Drug group or drug name | Drug examples | What can happen |
|---|---|---|
| certain antidepressants | • sertraline (Zoloft) • fluoxetine (Prozac) • venlafaxine (Effexor XR) | can increase the risk of irregular heart rhythm |
| certain antifungals | • ketoconazole • fluconazole (Diflucan) • itraconazole (Sporanox, Tolsura) | can increase the risk of irregular heart rhythm |
| certain antipsychotics | • aripiprazole (Abilify, Aristada, others) • brexpiprazole (Rexulti) • quetiapine (Seroquel, Seroquel XR) | can increase the risk of irregular heart rhythm |
| birth control pills | • ethinyl estradiol/levonorgestrel (Seasonale, Seasonique, others) • ethinyl estradiol/norethindrone acetate (Gildess, Junel, others) • desogestrel/ethinyl estradiol (Cyclessa, Kariva, others) | can make the birth control pills less effective |
| cholestyramine (LoCholest, Prevalite) | — | can make metronidazole less effective |
| cimetidine (Tagamet HB) | — | can increase the risk of side effects from metronidazole |
| busulfan (Myleran) | — | can increase the risk of side effects from busulfan |
| lithium (Lithobid) | — | can increase the risk of lithium toxicity |
| warfarin (Jantoven) | — | can increase the risk of bleeding |
| disulfiram | — | can lead to symptoms of psychosis (see “When should I avoid metronidazole?”) |
Certain health conditions or other factors could raise your risk of harm if you take metronidazole. These are known as contraindications. In such cases, your doctor may not prescribe this medication for you. The following list includes contraindications of metronidazole.
If you have Cockayne syndrome: If you have Cockayne syndrome (a rare inherited condition), your doctor likely will not prescribe metronidazole for you. This is because the drug could cause severe liver damage in people with this condition. Your doctor can recommend other treatments that may be safer options for you.
If you’re pregnant and have trichomoniasis: If you’re in the first trimester of pregnancy and have trichomoniasis (a parasitic infection), your doctor likely will not prescribe metronidazole for you. The drug may cause congenital anomalies (commonly known as birth defects) if it’s taken for this condition during this time. Your doctor can recommend other treatments that may be safer options for you.
If you consume alcohol: You should avoid consuming alcohol while taking metronidazole. This includes consuming prescription and over-the-counter drugs that contain propylene glycol or alcohol.
Consuming alcohol with metronidazole can lead to severe side effects, including:
- flushing
- headache
- abdominal cramps
- nausea or vomiting
Due to this risk, your doctor will advise you to avoid alcohol during metronidazole treatment and for at least 3 days after your final dose. If you have questions about metronidazole and alcohol, talk with your doctor.
If you’ve recently taken disulfiram: Your doctor is unlikely to prescribe metronidazole for you if you’ve taken disulfiram in the past 14 days. (Disulfiram is used for alcohol use disorder.) Taking these drugs together may lead to symptoms of psychosis. If you’ve recently taken disulfiram, your doctor can recommend alternatives to metronidazole that may be safer for you.
If you’ve had an allergic reaction: If you’ve had an allergic reaction to metronidazole or any of its ingredients, your doctor likely won’t prescribe metronidazole for you. This is because taking the drug could cause another allergic reaction. You can ask your doctor about other treatments that may be better options for you.
Before you start taking metronidazole, talk with your doctor if any of these factors apply to you. Your doctor can determine whether metronidazole is safe for you to take.
If you take metronidazole, you should avoid drinking alcohol during treatment and for at least 3 days after your final dose. For more information, see the “When should I avoid metronidazole?” section.
Learn more about certain drug interactions that can occur with metronidazole.
Interaction with certain antidepressants
Metronidazole can interact with certain antidepressants, which are used to treat mental health conditions.
Certain antidepressants may cause an irregular heart rhythm called long QT syndrome. In rare cases, this may lead to a life threatening condition called torsade de pointes. Taking certain antidepressants with metronidazole can raise the risk of this side effect.
Here are some antidepressants that can interact with metronidazole:
- sertraline (Zoloft)
- fluoxetine (Prozac)
- venlafaxine (Effexor XR)
What you can do
Before taking metronidazole, tell your doctor if you take an antidepressant. They’ll determine whether it’s safe to take these drugs together.
If you have questions about taking metronidazole with an antidepressant, talk with your doctor or pharmacist.
Interaction with cholestyramine
Metronidazole may interact with cholestyramine (LoCholest, Prevalite). This drug is used to help manage high cholesterol and high blood sugar.
Taking metronidazole with cholestyramine may make metronidazole less effective. This is because cholestyramine can prevent your body from fully absorbing metronidazole.
What you can do
If your doctor has you take these drugs together, they’ll likely advise you to take metronidazole at least 1 hour before or 4 hours after cholestyramine. This can help ensure that cholestyramine does not affect metronidazole.
If you have questions about taking metronidazole with cholestyramine, talk with your doctor or pharmacist.
Interaction with warfarin
Metronidazole may interact with warfarin (Jantoven), which is used to treat and help prevent blood clots.
Taking metronidazole with warfarin may enhance the blood-thinning effect of warfarin. This increased effect may raise the risk of bleeding as a side effect of warfarin.
What you can do
If you take metronidazole with warfarin, your doctor may order certain blood tests. They’ll do this to check the effect of warfarin in your body and monitor your risk of bleeding. If the test results show an increased risk of bleeding, your doctor may temporarily adjust your warfarin dosage while you’re taking metronidazole.
If you take these drugs together, tell your doctor right away if you have any unusual bleeding or bruising. They’ll recommend what to do.
If you have questions about taking metronidazole with warfarin, talk with your doctor or pharmacist.
Metronidazole may have other interactions. They could occur with supplements, foods, vaccines, or lab tests.
Here are additional interactions that may occur with metronidazole. Note that this information does not include all other possible interactions with metronidazole. For more information, you can refer to the prescription information for metronidazole oral capsules and oral tablets.
Does metronidazole interact with supplements?
Before you start taking metronidazole, talk with your doctor and pharmacist about any herbs, vitamins, or supplements you take. Sharing this information with them may help you avoid possible interactions.
If you have questions about interactions that may affect you, talk with your doctor or pharmacist.
Metronidazole and herbs
There are currently no reports of metronidazole oral capsules or oral tablets interacting with herbs. But this doesn’t mean that interactions with herbs won’t be recognized in the future.
For this reason, it’s important to check with your doctor or pharmacist before taking any of these products while taking metronidazole.
Metronidazole and vitamins
There are currently no reports of metronidazole oral capsules or oral tablets interacting with vitamins. But this doesn’t mean that vitamin interactions won’t be recognized in the future.
For this reason, it’s important to check with your doctor or pharmacist before taking any of these products while taking metronidazole.
Does metronidazole interact with food?
There are currently no reports of metronidazole oral capsules or oral tablets interacting with food. If you have questions about eating certain foods while taking metronidazole, talk with your doctor.
Does metronidazole interact with vaccines?
There are currently no reports of metronidazole oral capsules or oral tablets interacting with vaccines. If you have questions about getting certain vaccines during your metronidazole treatment, talk with your doctor.
Does metronidazole interact with lab tests?
Metronidazole may affect the results of specific lab tests, including:
If you have questions about getting any lab tests while taking metronidazole, talk with the healthcare professional ordering the test. They can tell you whether the test may be affected and whether you should wait until you’ve stopped taking metronidazole to have the test.
Does metronidazole interact with cannabis or CBD?There are currently no reports of metronidazole oral capsules or oral tablets interacting with cannabis (commonly called marijuana) or cannabis products such as cannabidiol (CBD). But as with any drug or supplement, talk with your doctor before using cannabis with metronidazole.
Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.
Certain medical conditions or other health factors may raise the risk of interactions with metronidazole. Before taking metronidazole, talk with your doctor about your health history. They’ll determine whether metronidazole is right for you.
Health conditions or other factors that might interact with metronidazole include:
Cockayne syndrome: If you have Cockayne syndrome, your doctor likely will not prescribe metronidazole for you. For details, see the “When should I avoid metronidazole?” section.
Kidney failure: If you have kidney failure, talk with your doctor before taking metronidazole. Having this condition may lead to a high level of the drug in your system, raising your risk of side effects. Your doctor can recommend whether metronidazole is a safe treatment option.
Liver problems: If you have a liver problem, such as liver failure, talk with your doctor before starting metronidazole. Having certain liver problems may increase your risk of side effects from the drug. To reduce this risk, your doctor may prescribe a lower metronidazole dosage than is typical.
Long QT syndrome: If you have an irregular heart rhythm called long QT syndrome, talk with your doctor before taking metronidazole. The drug may cause long QT syndrome as a side effect, which could worsen your condition. Your doctor can recommend whether metronidazole is safe for you.
Blood cell disorders: If you’ve ever had a blood cell disorder, talk with your doctor before taking metronidazole. The drug may worsen low white blood cell counts. Your doctor can advise you on whether metronidazole is a safe treatment option.
Pregnancy: If you’re in the first trimester of pregnancy and have contracted trichomoniasis, your doctor likely will not prescribe metronidazole for you. (For details, see the “When should I avoid metronidazole?” section.) It’s not known for certain whether metronidazole is safe to take past the first trimester of pregnancy. If you’re pregnant or planning a pregnancy, talk with your doctor about your options.
Breastfeeding: It’s not known whether it’s safe to take metronidazole while breastfeeding. The drug passes into breast milk, but it isn’t known whether the drug may cause side effects in a child who is breastfed. If you’re breastfeeding or planning to breastfeed, talk with your doctor about your options.
Allergic reaction: If you’ve had an allergic reaction to metronidazole or any of its ingredients, your doctor will likely not prescribe metronidazole. This is because taking the drug could cause another allergic reaction. You can ask your doctor about other treatments that may be better options for you.
Find answers to some frequently asked questions about metronidazole and possible interactions.
Are there specific foods to avoid while taking metronidazole?
Not necessarily. No specific foods have been reported to interact with metronidazole oral capsules or oral tablets.
Metronidazole is an antibiotic. And you may be advised to avoid dairy products with certain antibiotics, such as ciprofloxacin (Cipro). This is because the calcium in dairy products may affect how well the antibiotic works. However, calcium and dairy products are not known to affect metronidazole.
If you have other questions about metronidazole and food, talk with your doctor or pharmacist.
Can I take paracetamol and metronidazole together?
Yes, if your doctor recommends it. Paracetamol has not been reported to interact with metronidazole oral capsules or oral tablets.
In the United States, paracetamol is known as acetaminophen. It’s used to ease pain, fever, and inflammation.
If you need relief for pain, fever, or inflammation while taking metronidazole, talk with your doctor or pharmacist. They can recommend an appropriate treatment.
Taking certain steps can help you avoid interactions with metronidazole. Before starting treatment, talk with your doctor and pharmacist. Things to discuss with them include:
- whether you drink alcohol or use cannabis
- the
list of medications you take, as well as any vitamins, supplements, and herbs - what to do if you start taking a new drug during your metronidazole treatment
It’s also important to understand metronidazole’s
If you did not get paperwork with metronidazole, ask your pharmacist to print a copy for you. If you have trouble reading or understanding this information, your doctor or pharmacist can help.
Taking metronidazole exactly as prescribed can also help prevent interactions.
Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.