Table of ContentsView AllTable of ContentsUsesBefore TakingDosageSide EffectsWarnings and Interactions
Table of ContentsView All
View All
Table of Contents
Uses
Before Taking
Dosage
Side Effects
Warnings and Interactions
Metformin hydrochloride is an antihyperglycemic agent that helps lower production and absorption of glucose, as well as reduceinsulin resistance. It is typically used as an adjunct to diet and exercise to help managetype 2 diabetes. Glucophage was one brand of metformin, but it is no longer available.
Metformin belongs to a class of drugs calledbiguanides, which are derived from the French lilac flower. The drug comes in immediate-release (IR) or extended-release oral tablets (ER); extended-release metformin brands include Fortamet and Glumetza. Metformin is also available as a generic. Metformin is also available as an oral solution that you drink.
Nipitphon Na Chiangmai / EyeEm / Getty Images
According to the American Diabetes Association’s (ADA) Standards of Medical Care in Diabetes, metformin, if tolerated, is the preferred initial oral diabetes medication for type 2 diabetes because it is considered safe and effective, and it may reduce cardiovascular risks.
Metformin is approved for adults and children ages 10 and over. The extended-release formula is approved for use in those 18 and over.
Unlike people with type 1 diabetes, people with type 2 still produceinsulin(although production may decrease as the disease progresses). The problem is that they are either not making enough of the hormone or what they do make isn’t being used efficiently.
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This results in insulin resistance—the hormone is unable to direct sugar from the bloodstream to the cells for energy—and the liver and pancreas generate more insulin, even though it’s not needed. The body winds up in chaos, with both high blood sugars and high insulin levels.
Research shows that, as first-line therapy for type 2 diabetes, metformin has beneficial effects onA1C(a measure of average blood glucose), weight, and cardiovascular mortality compared to sulfonylureas.
Metformin may be used with insulin or otherdiabetes medicationsfor those with type 2 diabetes.
Updated ADA clinical guidelines recommend that patients with certain risk factors, including cardiovascular or kidney problems, receive another therapy alongside metformin to help delay treatment failure.
Combination medications that contain metformin, which may be recommended instead of metformin alone, if you need to take more than one drug, include:
Oral and Injectable Medications for Type 2 Diabetes
Off-Label Uses
In addition to being used for diabetes, metformin is sometimes used off-label in polycystic ovary syndrome (PCOS) as an aid for infertility, as a weight-loss adjunct, to treat gestational diabetes, or inHIV lipodystrophy syndrome.
Studies have also found that metformin targets many pathways in the growth of cancer, and research is evaluating the possible increased survival of those with cancers such aslung cancer,breast cancer, andbladder cancerwho have been treated with metformin.
Metformin is also being studied for its effect on the thyroid as it appears to reduce the risk ofgoiter,thyroid nodules, andthyroid cancer.
To assess if you’re a good candidate for metformin or another form of metformin, your healthcare provider willtest your blood glucoseand A1C levels to get a range of your current blood sugar control.
As metformin is typically part of the first line of defense when treating type 2 diabetes, you may start out on a low dosage with regular monitoring to see if glucose control improves.
Precautions and Contraindications
Certain medical circumstances can make takingmetformin riskyor even prohibit its use, including:
Talk to your healthcare provider about all medications, supplements, and vitamins that you currently take. While some drugs pose minor interaction risks, others may outright contraindicate use or prompt careful consideration.
Metformin does not directly reduce blood sugar in the same manner as insulin. Therefore, it is typically not appropriate for people with type 1 diabetes who require insulin.
Metformin is available in several dosages, including 500, 850, and 1,000 milligrams (mg) tablets. Glumetza, an extended-release form, comes in 500 or 1,000 mg tablets.
This medicine should be increased or titrated gradually to ease any stomach discomfort and to identify the lowest possible effective dose when it is first started.How long this takes depends on what your healthcare provider prescribes and how you respond to the medication.
For example, a person who is new to metformin and has been prescribed 2,000 mg might take the medication as follows:
A person who is prescribed 1,500 mg of extended-release metformin, for example, might take the medication as follows:
Throughout the duration of titration, your healthcare provider may ask you tomonitor your blood sugar. If you experiencehypoglycemia(low blood sugar) or any other side effects, contact your healthcare provider so that the medication can be adjusted accordingly.
If you miss a dose, try to take the missed pill as soon as possible, unless you’re approaching the time of your next regular dose.
Do not double up on the medication dose.
Modifications
Elderly patients should be kept on the lowest possible dose due to the potential for decreased kidney, liver, or heart function that may increase risk of lactic acidosis. Any dosage adjustment for those of advanced age should include a careful assessment of kidney function.
How to Take and Store
To remember to take metformin, you should try to take it around the same time(s) every day.
It is recommended that people take metformin with food because this increases its absorption in the stomach and reduces side effects (e.g., stomach cramps, diarrhea, and nausea). The extended-release version is usually taken once per day with the evening meal.
Store this medication at a controlled room temperature (ideally 68 to 77 degrees F). You can travel with it at temperatures ranging from 59 to 86 degrees F.
Generally, try to avoid skipping meals or drinking alcohol while taking this medication.
Most of the side effects of metformin are mild.
Common
Common side effects of metformin include:
If you are experiencing persistent side effects and are not already on the extended-release version of this drug, consider asking your doctor about making the switch. The time-released delivery may help prevent gastrointestinal side effects.
Unlike many treatments for diabetes, metformin does not typically cause hypoglycemia. Also, unlike many type 2 diabetes medications, metformin does not cause weight gain and may even help with weight loss.
Is Weight Loss a Side Effect of Metformin?
Severe
Lactic acidosis is a rare but serious side effect. Lactic acid builds up in the blood when the body has to metabolize sugars without adequate oxygen.
Although the latest studies suggest this may not be directly associated with metformin, the risk of lactic acidosis is increased in those with chronic kidney disease, liver, or heart disease.
If you experience any of the following, which includes symptoms of lactic acidosis as well as other serious reactions to metformin, seek medical help right away.
If lactic acidosis is not treated, it may result in severe complications or even death (cardiac arrest).
While you are taking metformin, your doctor will monitor your blood sugar levels and have you come in periodically for A1C testing to evaluate whether your dose or medication regimen needs to be adjusted. You may also need blood tests to monitor electrolytes and liver and kidney function.
Metformin may also result in a B12 deficiencydue to a complication known as pernicious anemia that can lead to permanent neurological damage.B12 deficiency is alsolinked with an increased risk of strokes. Early symptoms of B12 deficiency may include anemia, ringing in the ears, and depression. It’s important to have your B12 levels monitored since supplementation may be needed.
If metformin is inadequate to manage blood sugar,hyperglycemia(high blood sugar) may result. It’s important to monitor blood sugar levels at home and to seek immediate medical care if you experience any signs of dangerously high blood sugar, which can lead to loss of consciousness. This may include confusion, seizures, dry mouth, vomiting, or sweet-smelling breath.
Metformin may interact with numerous medications, which may impact the medication effects or lead to serious complications. There are also risks with certain medical tests or procedures, so always inform your healthcare provider and dentist that you are taking metformin.
Serious interactions that may occur when using metformin include:
In addition, anyone taking drugs or supplements that can lead to high blood sugar or loss of blood sugar control should have their blood levels carefully monitored while on metformin. The same is true for anyone who stops these treatments while on metformin.
Medications and supplements that can lead to hyperglycemia or loss of blood sugar control include:
May 28, 2020:The Food and Drug Administration (FDA) has requested that manufacturers of certain lots of metformin voluntarily withdraw the product from the market after the agency identified unacceptable levels of N-Nitrosodimethylamine (NDMA). Patients should continue taking their medications as prescribed until their healthcare professional prescribes an alternative treatment, if applicable. Stopping metformin without a replacement can pose serious health risks to patients with type 2 diabetes.
A Word From Verywell
While metformin is an excellent choice in addressing type 2 diabetes, lifestyle approaches such as a healthy diet and weight reduction (in those who are overweight) are the most important ways to manage insulin resistance and avoid the possible long-term consequences of diabetes. If metformin is prescribed to you, be sure to take it as prescribed and to check in with your doctor as recommended.
Common Signs Metformin Is Not Working and What to Do
14 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Nasri H, Rafieian-Kopaei M.Metformin: current knowledge.J Res Med Sci. 2014;19(7):658–664.American Diabetes Association.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes—2022. Diabetes Care. 2022;45(Supplement 1): S125–S143. doi:10.2337/dc22-S009Food and Drug Administration.Glucophage and Glucophage XR.Corcoran C, Jacobs TF.Metformin. In:StatPearls[Internet]. 2020.Maruthur NM, Tseng E, Hutfless S, et al.Diabetes medications as monotherapy or metformin-based combination therapy for type 2 diabetes: A systematic review and meta-analysis.Ann Intern Med.2016;164(11):740-51. doi:10.7326/M15-2650Lei Y, Yi Y, Liu Y, et al.Metformin targets multiple signaling pathways in cancer.Chin J Cancer. 2017;36(1):17. doi:10.1186/s40880-017-0184-9Meng X, Xu S, Chen G, Derwahl M, Liu C.Metformin and thyroid disease.J Endocrinol. 2017;233(1):R43-R51. doi:10.1530/JOE-16-0450Beysel S, Unsal IO, Kizilgul M, Caliskan M, Ucan B, Cakal E.The effects of metformin in type 1 diabetes mellitus.BMC Endocr Disord. 2018;18(1):1. doi:10.1186/s12902-017-0228-9Kanto K, Ito H, Noso S, et al.Effects of dosage and dosing frequency on the efficacy and safety of high-dose metformin in Japanese patients with type 2 diabetes mellitus.J Diabetes Investig. 2017;9(3):587–593. doi:10.1111/jdi.12755Kalra S, Mukherjee JJ, Venkataraman S, et al.Hypoglycemia: the neglected complication.Indian J Endocrinol Metab. 2013;17(5):819–834. doi:10.4103/2230-8210.117219Wang YW, He SJ, Feng X, et al.Metformin: a review of its potential indications.Drug Des Devel Ther. 2017;11:2421–2429. doi:10.2147/DDDT.S141675Kraut JA, Madias NE.Lactic acidosis: current treatments and future directions.Am J Kidney Dis. 2016;68(3):473-82. doi:10.1053/j.ajkd.2016.04.020Chapman LE, Darling AL, Brown JE.Association between metformin and vitamin B deficiency in patients with type 2 diabetes: a systematic review and meta-analysis. Diabetes Metab. 2016;42(5):316-327. doi:10.1016/j.diabet.2016.03.008Pakkir Maideen NM, Jumale A, Balasubramaniam R.Drug interactions of metformin involving drug transporter proteins.Adv Pharm Bull. 2017;7(4):501–505. doi:10.15171/apb.2017.062Additional ReadingKasper DL, Fauci AS, Hauser SL. Harrison’s principles of internal medicine. New York: McGraw-Hill Education, 2015. Print.Lalau JD, Kajbaf F, Protti A, et al.Metformin-associated lactic acidosis (MALA): Moving towards a new paradigm.Diabetes Obes Metab. 2017;19(11):1502-1512. doi:10.1111/dom.12974Thomas I, Gregg B.Metformin: A review of its history and future: From lilac to longevity. Pediatr Diabetes. 2017;18(1):10-16. doi:10.1111/pedi.12473
14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Nasri H, Rafieian-Kopaei M.Metformin: current knowledge.J Res Med Sci. 2014;19(7):658–664.American Diabetes Association.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes—2022. Diabetes Care. 2022;45(Supplement 1): S125–S143. doi:10.2337/dc22-S009Food and Drug Administration.Glucophage and Glucophage XR.Corcoran C, Jacobs TF.Metformin. In:StatPearls[Internet]. 2020.Maruthur NM, Tseng E, Hutfless S, et al.Diabetes medications as monotherapy or metformin-based combination therapy for type 2 diabetes: A systematic review and meta-analysis.Ann Intern Med.2016;164(11):740-51. doi:10.7326/M15-2650Lei Y, Yi Y, Liu Y, et al.Metformin targets multiple signaling pathways in cancer.Chin J Cancer. 2017;36(1):17. doi:10.1186/s40880-017-0184-9Meng X, Xu S, Chen G, Derwahl M, Liu C.Metformin and thyroid disease.J Endocrinol. 2017;233(1):R43-R51. doi:10.1530/JOE-16-0450Beysel S, Unsal IO, Kizilgul M, Caliskan M, Ucan B, Cakal E.The effects of metformin in type 1 diabetes mellitus.BMC Endocr Disord. 2018;18(1):1. doi:10.1186/s12902-017-0228-9Kanto K, Ito H, Noso S, et al.Effects of dosage and dosing frequency on the efficacy and safety of high-dose metformin in Japanese patients with type 2 diabetes mellitus.J Diabetes Investig. 2017;9(3):587–593. doi:10.1111/jdi.12755Kalra S, Mukherjee JJ, Venkataraman S, et al.Hypoglycemia: the neglected complication.Indian J Endocrinol Metab. 2013;17(5):819–834. doi:10.4103/2230-8210.117219Wang YW, He SJ, Feng X, et al.Metformin: a review of its potential indications.Drug Des Devel Ther. 2017;11:2421–2429. doi:10.2147/DDDT.S141675Kraut JA, Madias NE.Lactic acidosis: current treatments and future directions.Am J Kidney Dis. 2016;68(3):473-82. doi:10.1053/j.ajkd.2016.04.020Chapman LE, Darling AL, Brown JE.Association between metformin and vitamin B deficiency in patients with type 2 diabetes: a systematic review and meta-analysis. Diabetes Metab. 2016;42(5):316-327. doi:10.1016/j.diabet.2016.03.008Pakkir Maideen NM, Jumale A, Balasubramaniam R.Drug interactions of metformin involving drug transporter proteins.Adv Pharm Bull. 2017;7(4):501–505. doi:10.15171/apb.2017.062Additional ReadingKasper DL, Fauci AS, Hauser SL. Harrison’s principles of internal medicine. New York: McGraw-Hill Education, 2015. Print.Lalau JD, Kajbaf F, Protti A, et al.Metformin-associated lactic acidosis (MALA): Moving towards a new paradigm.Diabetes Obes Metab. 2017;19(11):1502-1512. doi:10.1111/dom.12974Thomas I, Gregg B.Metformin: A review of its history and future: From lilac to longevity. Pediatr Diabetes. 2017;18(1):10-16. doi:10.1111/pedi.12473
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Nasri H, Rafieian-Kopaei M.Metformin: current knowledge.J Res Med Sci. 2014;19(7):658–664.American Diabetes Association.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes—2022. Diabetes Care. 2022;45(Supplement 1): S125–S143. doi:10.2337/dc22-S009Food and Drug Administration.Glucophage and Glucophage XR.Corcoran C, Jacobs TF.Metformin. In:StatPearls[Internet]. 2020.Maruthur NM, Tseng E, Hutfless S, et al.Diabetes medications as monotherapy or metformin-based combination therapy for type 2 diabetes: A systematic review and meta-analysis.Ann Intern Med.2016;164(11):740-51. doi:10.7326/M15-2650Lei Y, Yi Y, Liu Y, et al.Metformin targets multiple signaling pathways in cancer.Chin J Cancer. 2017;36(1):17. doi:10.1186/s40880-017-0184-9Meng X, Xu S, Chen G, Derwahl M, Liu C.Metformin and thyroid disease.J Endocrinol. 2017;233(1):R43-R51. doi:10.1530/JOE-16-0450Beysel S, Unsal IO, Kizilgul M, Caliskan M, Ucan B, Cakal E.The effects of metformin in type 1 diabetes mellitus.BMC Endocr Disord. 2018;18(1):1. doi:10.1186/s12902-017-0228-9Kanto K, Ito H, Noso S, et al.Effects of dosage and dosing frequency on the efficacy and safety of high-dose metformin in Japanese patients with type 2 diabetes mellitus.J Diabetes Investig. 2017;9(3):587–593. doi:10.1111/jdi.12755Kalra S, Mukherjee JJ, Venkataraman S, et al.Hypoglycemia: the neglected complication.Indian J Endocrinol Metab. 2013;17(5):819–834. doi:10.4103/2230-8210.117219Wang YW, He SJ, Feng X, et al.Metformin: a review of its potential indications.Drug Des Devel Ther. 2017;11:2421–2429. doi:10.2147/DDDT.S141675Kraut JA, Madias NE.Lactic acidosis: current treatments and future directions.Am J Kidney Dis. 2016;68(3):473-82. doi:10.1053/j.ajkd.2016.04.020Chapman LE, Darling AL, Brown JE.Association between metformin and vitamin B deficiency in patients with type 2 diabetes: a systematic review and meta-analysis. Diabetes Metab. 2016;42(5):316-327. doi:10.1016/j.diabet.2016.03.008Pakkir Maideen NM, Jumale A, Balasubramaniam R.Drug interactions of metformin involving drug transporter proteins.Adv Pharm Bull. 2017;7(4):501–505. doi:10.15171/apb.2017.062
Nasri H, Rafieian-Kopaei M.Metformin: current knowledge.J Res Med Sci. 2014;19(7):658–664.
American Diabetes Association.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes—2022. Diabetes Care. 2022;45(Supplement 1): S125–S143. doi:10.2337/dc22-S009
Food and Drug Administration.Glucophage and Glucophage XR.
Corcoran C, Jacobs TF.Metformin. In:StatPearls[Internet]. 2020.
Maruthur NM, Tseng E, Hutfless S, et al.Diabetes medications as monotherapy or metformin-based combination therapy for type 2 diabetes: A systematic review and meta-analysis.Ann Intern Med.2016;164(11):740-51. doi:10.7326/M15-2650
Lei Y, Yi Y, Liu Y, et al.Metformin targets multiple signaling pathways in cancer.Chin J Cancer. 2017;36(1):17. doi:10.1186/s40880-017-0184-9
Meng X, Xu S, Chen G, Derwahl M, Liu C.Metformin and thyroid disease.J Endocrinol. 2017;233(1):R43-R51. doi:10.1530/JOE-16-0450
Beysel S, Unsal IO, Kizilgul M, Caliskan M, Ucan B, Cakal E.The effects of metformin in type 1 diabetes mellitus.BMC Endocr Disord. 2018;18(1):1. doi:10.1186/s12902-017-0228-9
Kanto K, Ito H, Noso S, et al.Effects of dosage and dosing frequency on the efficacy and safety of high-dose metformin in Japanese patients with type 2 diabetes mellitus.J Diabetes Investig. 2017;9(3):587–593. doi:10.1111/jdi.12755
Kalra S, Mukherjee JJ, Venkataraman S, et al.Hypoglycemia: the neglected complication.Indian J Endocrinol Metab. 2013;17(5):819–834. doi:10.4103/2230-8210.117219
Wang YW, He SJ, Feng X, et al.Metformin: a review of its potential indications.Drug Des Devel Ther. 2017;11:2421–2429. doi:10.2147/DDDT.S141675
Kraut JA, Madias NE.Lactic acidosis: current treatments and future directions.Am J Kidney Dis. 2016;68(3):473-82. doi:10.1053/j.ajkd.2016.04.020
Chapman LE, Darling AL, Brown JE.Association between metformin and vitamin B deficiency in patients with type 2 diabetes: a systematic review and meta-analysis. Diabetes Metab. 2016;42(5):316-327. doi:10.1016/j.diabet.2016.03.008
Pakkir Maideen NM, Jumale A, Balasubramaniam R.Drug interactions of metformin involving drug transporter proteins.Adv Pharm Bull. 2017;7(4):501–505. doi:10.15171/apb.2017.062
Kasper DL, Fauci AS, Hauser SL. Harrison’s principles of internal medicine. New York: McGraw-Hill Education, 2015. Print.Lalau JD, Kajbaf F, Protti A, et al.Metformin-associated lactic acidosis (MALA): Moving towards a new paradigm.Diabetes Obes Metab. 2017;19(11):1502-1512. doi:10.1111/dom.12974Thomas I, Gregg B.Metformin: A review of its history and future: From lilac to longevity. Pediatr Diabetes. 2017;18(1):10-16. doi:10.1111/pedi.12473
Kasper DL, Fauci AS, Hauser SL. Harrison’s principles of internal medicine. New York: McGraw-Hill Education, 2015. Print.
Lalau JD, Kajbaf F, Protti A, et al.Metformin-associated lactic acidosis (MALA): Moving towards a new paradigm.Diabetes Obes Metab. 2017;19(11):1502-1512. doi:10.1111/dom.12974
Thomas I, Gregg B.Metformin: A review of its history and future: From lilac to longevity. Pediatr Diabetes. 2017;18(1):10-16. doi:10.1111/pedi.12473
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