Information 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.
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 ovarian syndrome.
Metformin works very well and is generally safe.
What are some examples of metformin?
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 (Glumetza)
Sometimes metformin is combined with other diabetes medicine.
- Avandamet is a combination of metformin and rosiglitazone.
- Janumet is a combination of metformin and sitagliptin.
- Jentadueto is a combination of metformin and linagliptin.
This is not a complete list.
What about side effects?
When they first start taking metformin or start taking a larger dose, some people feel sick to their stomach or have diarrhea for a short time.
Over time, blood levels of vitamin B12 can decrease in some people who take metformin. Your body needs this B vitamin to make blood cells and to keep your nervous system healthy. If you have been taking metformin for more than a few years, ask your doctor if you need a B12 blood test to measure the amount of vitamin B12 in your blood.
General information on 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. He or she may be able to lower your dose or change to a different medicine. Don't suddenly stop taking your medicine without talking to your doctor first.
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.
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. 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.
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 to unborn babies and newborns: If you are pregnant, trying to get pregnant, or breastfeeding, ask your doctor or pharmacist if any of the medicines you take could harm your baby.
- Other health problems: Before taking a medicine, be sure your doctor or pharmacist knows about all your health problems. Other health problems may affect your medicine. Or 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 and natural health products. 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.
Other Works Consulted
- American Diabetes Association (2018). Standards of medical care in diabetes—2018. Diabetes Care, 41(Suppl 1): S1–S159. http://care.diabetesjournals.org/content/41/Supplement_1. Accessed December 8, 2017.
- Inzucchi SE, et al. (2015). Management of hyperglycemia in type 2 diabetes, 2015: A patient-centered approach: Update to a position statement of the American Diabetes Association and the European Association for the Study of Diabetes. Diabetes Care, 38(1): 140–149. DOI: 10.2337/dc14-2441. Accessed February 18, 2015.
Current as of: December 20, 2019
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