Metformin oral tablet is a generic prescription drug used to help manage high blood sugar levels in people with type 2 diabetes. It can interact with alcohol, other medications, and some supplements, including hydrochlorothiazide and topiramate.
Metformin is available as the brand-name drug Glumetza.
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.
Keep reading to learn about metformin’s possible interactions. And for more information about metformin, including details about its uses, see this article.
Before you start taking metformin, tell your doctor and pharmacist about any prescription, over-the-counter, or other drugs you take. Sharing this information with them may help prevent possible interactions. (To learn whether metformin interacts with herbs, vitamins, or supplements, see the “Are there other interactions with metformin?” section.)
If you have questions about drug interactions that may affect you, talk with your doctor or pharmacist.
The table below lists drugs that may interact with metformin. Keep in mind that this table does not include all drugs that may interact with metformin. For more information about some of these interactions, see the “Drug interactions explained” section.
| Drug group or drug name | Drug examples | What can happen |
|---|---|---|
| isoniazid | — | can make metformin less effective |
| niacin (Niaspan, Niacor) | — | can make metformin less effective |
| ranolazine (Ranexa) | — | can increase the risk of side effects of metformin |
| dolutegravir (Tivicay) | — | can increase the risk of side effects of metformin |
| cimetidine (Tagamet HB) | — | can increase the risk of side effects of metformin |
| certain diabetes drugs | • insulin glargine (Lantus) • glipizide (Glucotrol XL) | can increase the risk of low blood sugar levels |
| carbonic anhydrase inhibitors | • topiramate (Topamax, others) • acetazolamide | can increase the risk of lactic acidosis |
| diuretics (water pills) | • hydrochlorothiazide (Microzide) • furosemide (Lasix) | can make metformin less effective |
| corticosteroids | • prednisone (Rayos) • budesonide | can make metformin less effective |
| estrogens | • estradiol • hormonal birth control | can make metformin less effective |
Certain health conditions or other factors could raise your risk of harm if you take metformin. In such cases, your doctor may not prescribe metformin for you. These are known as contraindications. The list below includes contraindications of metformin.
If you have severe kidney problems: If you have severe kidney problems, your doctor likely won’t prescribe metformin. This is because you may be at higher risk of lactic acidosis. Due to this risk, your doctor may order tests to check your kidney health before you start metformin.
If you have metabolic acidosis: If you have metabolic acidosis, including diabetic ketoacidosis, your doctor likely won’t prescribe metformin. This is because metformin can worsen your condition. Ask your doctor about alternative treatments that may be safer for you.
If you’ve had an allergic reaction: If you’ve had an allergic reaction to metformin or any of its ingredients, your doctor likely won’t prescribe metformin 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 metformin, talk with your doctor if any of the factors above apply to you. Your doctor can determine whether metformin is safe for you to take.
You should not take metformin with alcohol.
Consuming large amounts of alcohol while taking metformin can increase your risk of lactic acidosis. Metformin oral tablet has a boxed warning about the risk of lactic acidosis. To learn more, see the top of this article.
In addition, alcohol and metformin can both lower your blood sugar. Drinking alcohol while taking metformin could increase your risk of low blood sugar levels.
If you have questions about consuming alcohol while taking metformin, talk with your doctor or pharmacist.
Learn more about certain drug interactions that can occur with metformin.
Interaction with certain diabetes drugs
Metformin can interact with certain diabetes drugs, including insulin drugs and medications that help insulin better respond to the body.
Diabetes medications that interact with metformin include:
What could happen
Taking metformin with certain diabetes drugs can raise your risk of low blood sugar levels as a side effect of metformin or the other diabetes medication.
What you can do
If you take metformin with certain diabetes medications, your doctor may prescribe a dosage of metformin that’s lower than usual. You should not take a higher dose of either medication than your doctor prescribes.
If you develop any signs or symptoms of low blood sugar levels, tell your doctor right away. These may include:
- shaking
- sweating
- dizziness
- headache
- blurry vision
- hunger
- pale skin
To learn more, talk with your doctor or pharmacist.
Interaction with diuretics
Diuretics, or water pills, are drugs used to reduce the amount of fluid in your blood vessels. They help increase the amount of water and salt expelled from your body as urine. Diuretics are most commonly used to treat high blood pressure.
Here are some examples of diuretic medications:
- furosemide (Lasix)
- hydrochlorothiazide (Microzide)
- chlorthalidone (Thalitone)
- ethacrynic acid (Edecrin)
- metolazone
- torsemide (Demadex)
- bumetanide
What could happen
Diuretics can cause high blood sugar levels. Because metformin is used to lower blood sugar levels caused by type 2 diabetes, taking these drugs together can make metformin less effective.
What you can do
Before you start metformin, tell your doctor if you take a diuretic. They may adjust the dose of your diuretic or metformin to help minimize the risk of an interaction.
Interaction with ranolazine
Ranolazine (Ranexa) is a heart medication used to treat chest pain.
What could happen
If you take ranolazine and metformin together, your risk of side effects from metformin, including lactic acidosis, can increase. This is because ranolazine interferes with the way metformin is cleared from your body. If metformin cannot be cleared as quickly as usual, it can build up in your system and increase your risk of side effects.
What you can do
Be sure to tell your doctor if you take ranolazine before you start metformin. In some cases, they may not prescribe these drugs together. If you and your doctor decide it’s safe for you take metformin and ranolazine together, your doctor will likely prescribe a lower dose of metformin.
Metformin may have other interactions. They could occur with supplements, foods, vaccines, or even lab tests. See below for details. Note that this information does not include all other possible interactions with metformin.
Does metformin interact with supplements?
Before you start taking metformin, 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.
Metformin may interact with garlic supplements. Taking metformin with garlic supplements can increase the risk of low blood sugar levels. Due to this risk, your doctor may reduce your dosage of metformin or recommend that you stop taking garlic supplements.
If you have questions about interactions that may affect you, talk with your doctor or pharmacist.
Metformin and herbs
There are currently no reports of metformin interacting with herbs. But this doesn’t mean that interactions with herbs won’t be recognized in the future.
For this reason, it’s still important to check with your doctor or pharmacist before taking any of these products while taking metformin.
Metformin interactions with vitamins and minerals
Metformin may interact with chromium supplements. This mineral is used to support several bodily functions, including boosting the effects of insulin.
Taking metformin with chromium supplements can increase your risk of low blood sugar levels.
Due to this risk, it’s important that you talk with your doctor or pharmacist before taking chromium supplements with metformin.
Does metformin interact with food?
Metformin can interact with green tea. Green tea may help reduce blood sugar in certain situations.
Consuming green tea while taking metformin can increase your risk of low blood sugar levels.
If you have questions about consuming green tea while taking metformin, talk with your doctor.
Does metformin interact with vaccines?
There are currently no reports of metformin interacting with vaccines. If you have questions about getting certain vaccines during your metformin treatment, talk with your doctor.
Does metformin interact with lab tests?
There are currently no reports of metformin interacting with lab tests. If you have questions about having certain lab tests done during your treatment with metformin, talk with the healthcare professional ordering the test.
Does metformin interact with cannabis or CBD?There are currently no reports of metformin 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 metformin.
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 metformin. Before taking metformin, talk with your doctor about your health history. They’ll determine whether metformin is right for you.
Health conditions or other factors that might interact with metformin include:
Liver problems: Your liver helps clear lactic acid from your body. If you have liver problems, your body may clear lactic acid more slowly than usual. This can increase your risk of lactic acidosis while taking metformin. (Metformin has a boxed warning about the risk of lactic acidosis.)
Kidney problems: Your kidneys help clear metformin from your body. If you have kidney problems, your body may not clear metformin as quickly as usual. This can cause metformin to build up in your body, which can increase your risk of lactic acidosis.
Planned surgery: Tell your doctor if you have a planned surgery or procedure. Withholding food or fluids for a procedure can decrease your kidney function. This can increase your risk of lactic acidosis as a side effect of metformin. Due to this risk, your doctor may have you temporarily stop metformin while you prepare for your procedure.
Imaging procedure: In some cases, imaging procedures require an injection of dye. Some dyes can decrease your kidney function, which will increase your risk of lactic acidosis. If you have an imaging procedure planned, tell your doctor. They can help determine whether you need to temporarily stop taking metformin and when it’s safe to restart treatment.
Heart problems: Certain heart problems, such as heart attack or heart failure, can increase your risk of lactic acidosis as a side effect of metformin. Additionally, metformin can cause changes in heart rate. If you have a history of heart problems, metformin can worsen your condition.
Older age: People ages 80 years and older may have decreased kidney function, which can increase the risk of lactic acidosis. If you’re 80 years old or older, your doctor will likely order tests to check your kidney health before you start metformin.
Pregnancy: It’s not known whether metformin is safe to take during pregnancy. If you’re pregnant or planning a pregnancy, talk with your doctor before taking metformin.
Breastfeeding: It’s not known whether it’s safe to take metformin while breastfeeding. The drug passes into breast milk, but it isn’t known whether the drug may cause side effects in a child who’s 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 metformin or any of its ingredients, your doctor will likely not prescribe metformin. This is because taking the drug could cause another allergic reaction. You can ask your doctor about other treatments that may be better choices for you.
Find answers to some frequently asked questions about metformin and possible interactions.
Is there an interaction between metformin and ibuprofen?
No. There’s no known interaction between metformin and ibuprofen.
However, ibuprofen can cause kidney problems. Your kidneys help clear metformin from your body. If you have kidney problems, your body may not clear metformin as quickly as usual. This can increase the levels of metformin in your body, which increases the risk of side effects of metformin, including lactic acidosis.
If you have more questions about taking ibuprofen with metformin, talk with your doctor.
Can I take acetaminophen if I’m taking metformin?
In general, yes, it’s safe to take acetaminophen (Tylenol) with metformin. There are no reports of these medications interacting with each other.
Before taking acetaminophen or any other over-the-counter medication, talk with your doctor or pharmacist. They can advise you on whether the medication is safe for you and what the right dosage is.
Taking certain steps can help you avoid interactions with metformin. Before starting treatment, talk with your doctor and pharmacist. Things to discuss with them include:
- whether you drink alcohol or use cannabis
- other medications you take, as well as any vitamins, supplements, and herbs (they can also help you fill out a
medication list ) - what to do if you start taking a new drug during your metformin treatment
It’s also important to understand metformin’s
If you have trouble reading or understanding this information, your doctor or pharmacist can help.
Taking metformin 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.