Metformin

Metformin is a prescription-only oral medicine used to help control blood sugar in type 2 diabetes. Metformin is used for Type 2 diabetes. It carries a boxed warning: risk of lactic acidosis.

Also called: Glumetza (United States) · Sukkarto (United Kingdom) · Glycon (Canada) · Diabex (Australia) · Meidikang (China)

Pronunciation: met-FOR-min.

Generic name
metformin hydrochloride
Drug class
Biguanide (oral antidiabetic)
Form
Tablet or extended-release tablet (500 mg, 850 mg, 1000 mg)
Route
Oral
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · India · Nepal · New Zealand · China

Australia: Diabex, METFORMIN-WGR, Metformin Sandoz, Diaformin, APX-METFORMIN, Blooms The Chemist Metformin, Diaformin Viatris, FORMET · Full directory

What metformin hydrochloride is and how it works

Metformin is a prescription-only oral medicine used to help control blood sugar in type 2 diabetes. It is usually the first medicine tried for type 2 diabetes and is often combined with other diabetes medicines. (1)

Take metformin exactly as your prescriber directs, with meals, to reduce stomach upset. Your prescriber will check your kidney function before starting and periodically afterward, since this affects your dose and safety.

Mechanism of action: how metformin hydrochloride works

Metformin decreases hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake and utilisation. (1)

What is Metformin hydrochloride used for?

Type 2 diabetes

Used together with diet and exercise to improve blood sugar control in adults and children aged 10 and older with type 2 diabetes. (1)

Before taking metformin hydrochloride

Do not take / not appropriate for

  • Do not take metformin if you have severe kidney problems (eGFR below 30). (all countries) (1)
  • Do not take metformin if you have diabetic ketoacidosis or any other acute or chronic metabolic acidosis. (all countries) (1)
  • Do not take metformin if you have had a serious allergic reaction to it. (all countries) (1)

Tell your clinician about

  • Any kidney or liver problems.
  • Heart failure or any condition causing low oxygen levels in the body.
  • How much alcohol you drink.
  • Any upcoming surgery or imaging tests that use injected contrast dye.
  • Pregnancy, plans for pregnancy, or breastfeeding.
(1)

Metformin hydrochloride dosage and how to take it

  • Take metformin with meals to reduce stomach upset.
  • Swallow extended-release tablets whole -- do not split, crush, or chew them.
  • Your prescriber will start you on a low dose and increase it gradually over several weeks.
  • Before any surgery or imaging test using injected contrast dye, your prescriber may tell you to stop metformin temporarily -- follow their specific instructions.
(1)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5)

Missed dose

Take your next dose at the regular scheduled time. Do not take an extra dose to make up for a missed one.

Overdose

Seek urgent medical attention or contact your prescriber immediately if too much metformin has been taken. (1)

Metformin hydrochloride side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Diarrhoea, nausea, and vomiting are common, especially when starting treatment.

What to notice: Diarrhoea, nausea, and vomiting are common, especially when starting treatment.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Gas, weakness, indigestion, stomach discomfort, and headache.

What to notice: Gas, weakness, indigestion, stomach discomfort, and headache.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Signs of lactic acidosis — boxed_warning

Symptoms: Feeling generally unwell, muscle pain, difficulty breathing, unusual tiredness or sleepiness, low body temperature, slow or irregular heartbeat, or stomach pain.

Action: Seek urgent medical attention immediately if this is suspected -- the treating team will stop metformin as part of hospital care. (1)

Signs of vitamin B12 deficiency — high caution

Symptoms: Unusual tiredness, numbness or tingling in the hands or feet, or memory problems.

Action: Tell your prescriber -- long-term metformin use can lower vitamin B12 levels, which are checked periodically. (1)

Interactions

  • Certain medicines that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) can increase metformin levels -- tell your prescriber about all other medicines you take. (1)
  • Drinking alcohol, especially in excess, increases the risk of lactic acidosis with metformin. (1)
  • Taking metformin with insulin or a sulfonylurea increases the risk of low blood sugar -- your prescriber may adjust those doses. (1)
  • Medicines that treat glaucoma or altitude sickness (carbonic anhydrase inhibitors) can increase the risk of lactic acidosis if combined with metformin. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

There is limited data on metformin use in pregnancy, not enough to determine whether it increases the risk of birth defects. Animal studies did not show harmful effects on the developing baby. Discuss with your prescriber if you are pregnant or planning pregnancy. (1)

Breastfeeding

Metformin passes into breast milk in small amounts. Discuss with your prescriber. (1)

Children

Approved for children aged 10 and older with type 2 diabetes, at a lower maximum dose than adults. (1)

Elderly

People over 65 have a higher risk of lactic acidosis -- kidney function should be checked more often. (1)

Hepatic Impairment

Liver impairment increases the risk of lactic acidosis -- tell your prescriber about any liver problems. (1)

Renal Impairment

Contraindicated if eGFR is below 30; not recommended to start if eGFR is 30-45; kidney function should be checked before starting and periodically during treatment. (1)

Monitoring

Before starting

  • Kidney function (eGFR)
  • Liver function if relevant
  • Vitamin B12 level (baseline useful for long-term monitoring)

During treatment

  • Periodic kidney function checks.
  • Vitamin B12 levels checked annually.
  • Blood sugar (HbA1c) monitoring to assess response.
(1)

Storage

Store at room temperature, away from moisture and heat. Keep out of the reach of children.

Study the drug class: Biguanides (practice MCQs)

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information; verify against the current full label before prescribing.

United States

Indication: Type 2 diabetes

Dose summary: Adults: start 500mg BID or 850mg once daily with meals; titrate by 500mg/week or 850mg/2 weeks; max 2,550mg/day divided. Children 10+: start 500mg BID; max 2,000mg/day divided. Contraindicated eGFR <30; do not initiate 30-45. Stop at/before iodinated contrast procedures, may resume 48h later if renal function stable.

Renal context: Contraindicated below eGFR 30 mL/min/1.73m2; not recommended to initiate at eGFR 30-45; assess eGFR before starting and periodically. (1)

Mechanism of action

Hepatic guidance

Hepatic impairment is a risk factor for lactic acidosis; use with caution and closer monitoring.

Overdose note

Hemodialysis is effective at removing metformin and correcting lactic acidosis in overdose; manage supportively and seek urgent guidance. (1)

Frequently asked questions

Is metformin available in the US, UK, Europe, Canada, and Australia?

Yes -- metformin is one of the most widely available medicines in the world. The US prescribing information is published on DailyMed, multiple UK marketing authorisations are listed on the electronic medicines compendium, Health Canada's Drug Product Database lists many metformin products, and Australia's TGA lists multiple ARTG registrations. Its use for diabetes was first reported in 1957, it was introduced in the USA in 1995, and it has become the most prescribed glucose-lowering medicine worldwide. New Zealand-specific confirmation was not found in this research but availability there is highly likely given its global ubiquity. (1) (2) (4) (5) (3)

Why do I need to stop metformin before a scan with contrast dye?

Contrast dye used in some imaging tests can temporarily affect kidney function, and metformin relies on the kidneys to be cleared from the body. Stopping it around the time of the procedure reduces the risk of lactic acidosis; your prescriber will tell you exactly when to stop and restart. (1)

What are the warning signs of lactic acidosis with metformin?

Lactic acidosis is rare but serious, and can be fatal. Warning signs include unusual muscle pain, difficulty breathing, unusual tiredness, stomach pain with nausea or vomiting, feeling cold, dizziness, or a slow or irregular heartbeat. Seek emergency medical care immediately if these occur, especially if you also have kidney problems or another risk factor your prescriber has discussed with you -- do not decide on your own whether to keep taking metformin, let the treating team make that call once you're being seen. (1)

What is the mechanism of action of metformin hydrochloride?

Metformin decreases hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake and utilisation. (1)

What is the generic name of Metformin?

The generic name is metformin hydrochloride. (1)

What class of drug is metformin hydrochloride?

Metformin is classed as: Biguanide (oral antidiabetic). (1)

References

  1. METFORMIN HYDROCHLORIDE tablets -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · accessed 2026-07-29 · source 1
  2. Metformin: historical overviewBailey CJ, 'Metformin: historical overview', Diabetologia 2017;60:1566-1576 (PubMed-indexed peer-reviewed review) · Global · accessed 2026-08-17 · source 2
  3. Multiple metformin products -- ARTG registrationsTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-29 · source 3
  4. Metformin -- UK marketing authorisations and SmPCselectronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-08-17 · source 4
  5. Metformin hydrochloride -- Drug Product Database active ingredient listingHealth Canada Drug Product Database · Canada · accessed 2026-08-17 · source 5

Brand names by country

Single-ingredient metformin hydrochloride names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Glumetzatablet, film coated, extended release · 500 mg, 1000 mg · santarus, inc.regulator source
  • Riometsolution · 500 mg/5mL · sun pharmaceutical industries, inc.regulator source

India

Source-listed products; local stock and regulatory approval have not been confirmed. Check the exact ingredient, strength, and formulation with a pharmacist.

  • Glycomet 500 SR TabletTablet SR · 500mg · USV Private Limitedpharmacy source · checked 2026-09-24
  • Okamet 500 TabletTablet · 500mg · Cipla Ltdpharmacy source · checked 2026-09-24
  • Debistal 500 SR TabletTablet SR · 500mg · Leeford Healthcare Ltdpharmacy source · checked 2026-09-24
  • Metform 1000mg Tablet SRTablet SR · 1000mg · Knoll Pharmaceuticals Ltdpharmacy source · checked 2026-09-24
  • Abomet 1000mg Tablet SRTablet SR · 1000mg · Abbottpharmacy source · checked 2026-09-24
  • Dailyglim 500 SR TabletTablet PR · 500mg · Leeford Healthcare Ltdpharmacy source · checked 2026-09-24
  • Exermet 500 SR TabletTablet PR · 500mg · Cipla Ltdpharmacy source · checked 2026-09-24
  • Biciphage 500 TabletTablet · 500mg · Biochem Pharmaceutical Industriespharmacy source · checked 2026-09-24
  • Glyciphagetablet · 500 mg · Franco-Indian Pharmaceuticals Pvt Ltdpharmacy source
  • Gluformintablet · 500 mg · Abbott Healthcare Private Limitedpharmacy source
  • Obimettablet · 500 mg · Corona Remedies Pvt Ltdpharmacy source
  • Melmettablet · Micro Labs Ltdpharmacy source
  • Metsmalltablet · Dr Reddy's Laboratories Ltdpharmacy source
  • Metadozetablet · Eris Lifesciences Limitedpharmacy source
  • Gluconormtablet · Lupin Ltdpharmacy source
  • X Mettablet · Glenmark Pharmaceuticals Ltdpharmacy source

Nepal

Source-listed products; local stock and regulatory approval have not been confirmed. Check the exact ingredient, strength, and formulation with a pharmacist.

  • AROMETTablet · 500mg · Arrow pharmaceuticals pvt Ltdreference source · checked 2026-09-24
  • BigometTablet · 850 mg · Aristo Pharmaceuticals Ltd.reference source · checked 2026-09-24
  • BiometSR Tablet · 1gm · Aristo Pharmaceuticals Ltd.reference source · checked 2026-09-24
  • CarbometTablet · 500mg · CTL Pharmaceuticals Pvt. Ltd.reference source · checked 2026-09-24
  • EffimetTablet · 1gm · Deurali Janta Pharmaceuticals Pvt. Ltd.reference source · checked 2026-09-24
  • FormetTablet · 1gm · Lomus Pharmaceutical Pvt. Ltd.reference source · checked 2026-09-24
  • Formin 500Tablet · 500mg · Nepal Pharmaceuticals Pvt. Ltd.reference source · checked 2026-09-24
  • Forminal 500Tablet · 500mg · Alembic Pharmaceuticals Ltd.reference source · checked 2026-09-24
  • Metfortablet · 500 mg · Quest Pharmaceuticals (P.) Ltd.pharmacy source
  • Glycomettablet · USV Ltd. (Indian import)pharmacy source

New Zealand

  • Metformin (Apotex)film-coated tablet · 500 mg, 850 mg, 1000 mg · Apotex NZ Ltdregulator source
  • Metformin Viatristablet · 500 mg, 850 mg, 1000 mg · Viatris Ltd (formerly Mylan; data sheet formerly 'Metformin Mylan')regulator source
  • Indoco Metforminfilm-coated tablet · 500 mg, 850 mg · Miro Healthcare Ltd, Auckland (sponsor named in section 8 of the data sheet)regulator source

China

  • Glucophagetablet (盐酸二甲双胍片) · 0.5 g · 中美上海施贵宝制药有限公司 (Sino-American Shanghai Squibb, as shown on source)pharmacy source
  • Meidikangtablet (盐酸二甲双胍片) · 深圳市中联制药有限公司 (as shown on source)pharmacy source
  • Taibaitablet, extended-release tablet (缓释片) · listed as domestic single-ingredient metformin brand in a top-10 brand rankingpharmacy source
  • Yuedaninglisted as single-ingredient 盐酸二甲双胍 brand in a top-10 brand rankingpharmacy source
  • Bukelisted as single-ingredient metformin brand in a top-10 brand rankingpharmacy source
View brands in additional countries.

Philippines

Glucophage, Glumet, Gludin, Glyformet, Metta, Normax, Sucranorm, Neoform

Pakistan

Glucophage, Neodipar, Neophage, Glucoformin, Glumet, Diabimin, Comet

Bangladesh

Comet, Informet, Nobesit, Bigmet, Metfo, Daomin, Metform, Glucomet, Oramet, Glunor

Indonesia

Glucophage, Glumin XR, Gludepatic 500, Eraphage, Forbetes, Nevox XR, Glufor

Nigeria

Glucophage / Glucophage XR, Diamet / Diamet SR, Panfor SR 500, Biophage, Avrophage, Glyformin, Glucoform, Glylow / Glylow SR, Sealmet 1000, Betaform 500

Brazil

Glifage, Glifage XR, Formyn, Diglixx, Glicomet, Glicefor, Meglize

Russia

Glucophage / Glucophage Long, Siofor / Siofor Long, Formetin / Formetin Long, Merifatin, Metformin Sanofi, Metformin Renewal

Mexico

Glucophage, Dimefor / Dimefor XR, Dabex XR, Predial / Predial Plus, Ficonax, Pharmafet / Pharmafet Lb

European Union

Metformin (generic) (2)

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