Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.
Metformin for Diabetes
About This Medicine
What are the most important things you need to know about your medicines?
Make sure you know about each of the medicines you take. This includes why you take it, how to take it, what you can expect while you're taking it, and any warnings about the medicine.
The information provided here is general. So be sure to read the information that came with your medicine. If you have any questions or concerns, talk to your pharmacist or doctor.
What are some examples?
Here are some examples of metformin. For each item in the list, the generic name is first, followed by any brand names.
- metformin (Glucophage)
- long-acting metformin (Glucophage XR, Glumetza, Fortamet)
- liquid metformin (Riomet)
Sometimes metformin is combined with other diabetes medicine.
- Avandamet is a combination of metformin and rosiglitazone.
- Glucovance is a combination of metformin and glyburide.
- Janumet is a combination of metformin and sitagliptin.
This is not a complete list.
Why is metformin used?
Metformin is a medicine used to treat prediabetes, type 2 diabetes, and gestational diabetes. It helps control your blood sugar. It is also used to treat polycystic ovary syndrome.
Metformin works very well and is generally safe.
What about side effects?
When you first start taking metformin or take a larger dose, you may feel sick to your stomach or have diarrhea for a short time.
Blood levels of vitamin B12 may decrease when you take metformin. If you have been taking metformin, ask your doctor if you need a B12 blood test.
General information about side effects
All medicines can cause side effects. Many people don't have side effects. And minor side effects sometimes go away after a while.
But sometimes side effects can be a problem or can be serious.
If you're having problems with side effects, talk to your doctor. Your doctor may be able to lower your dose or change to a different medicine.
Always be sure you get specific information on the medicine you're taking. For a full list of side effects, check the information that came with the medicine you're using. If you have questions, talk to your pharmacist or doctor.
What are some cautions about metformin?
Cautions for metformin include the following:
- Contrast dyes used in X-rays, scans, and surgeries can cause a serious problem called lactic acidosis if you are taking metformin and have severe kidney disease. Be sure all your doctors know that you take this medicine if you need a test that involves the use of a dye or if you have surgery. You may have to stop taking metformin for a while.
- Metformin does not usually cause low blood sugar. But you may have low blood sugar if you take it with medicines that do, or if you exercise very hard, drink alcohol, or do not eat enough.
General cautions for all medicines
- Allergic reactions.
- All medicines can cause a reaction. This can sometimes be an emergency. Before you take any new medicine, tell the doctor or pharmacist about any past allergic reactions you've had.
- Drug interactions.
- Sometimes one medicine may keep another medicine from working well. Or you may get a side effect you didn't expect. Medicines may also interact with certain foods or drinks, like grapefruit juice and alcohol. Some interactions can be dangerous.
- Harm during pregnancy or breastfeeding.
- If you are pregnant, trying to get pregnant, or breastfeeding, ask your doctor or pharmacist if all the medicines you take are safe.
- Other health problems.
- Before taking a medicine, be sure your doctor or pharmacist knows about all your health problems. The medicine for one health problem may affect another health problem.
Always tell your doctor or pharmacist about all the medicines you take. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. That information will help prevent serious problems.
Always be sure you get specific information on the medicine you're taking. For a full list of warnings, check the information that came with the medicine you're using. If you have questions, talk to your pharmacist or doctor.
Current as of: April 13, 2022
Author: Healthwise Staff
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
Theresa O'Young PharmD - Clinical Pharmacy
David C.W. Lau MD, PhD, FRCPC - Endocrinology
To learn more about Healthwise, visit Healthwise.org.
© 1995-2022 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.