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Metformin, often sold under names such as Glucophage, is an oral biguanide commonly used to treat type 2 diabetes. It lowers blood glucose primarily by reducing liver glucose output, slowing absorption of glucose from the gut, and improving how muscle and fat tissues respond to insulin.

As monotherapy metformin rarely causes low blood sugar. Many people taking it notice stable weight or modest weight loss. It requires some insulin activity to be effective and is not a substitute for insulin in type 1 diabetes.

The active ingredient is metformin hydrochloride. In Australia immediate-release tablets are commonly available in 250 mg, 500 mg, 850 mg and 1000 mg strengths; extended-release formulations include 500 mg, 750 mg and 1000 mg XR products. For urgent scenarios such as acute illness or contrast imaging, see the essential precautions section here plus the disclaimer: Use the information at your own risk, as it may not be current or complete. here.

Who this product is for

Metformin is a first-line drug for many adults with type 2 diabetes after lifestyle measures like diet and exercise. It is often combined with other glucose-lowering medicines when additional control is needed.

• Adults with newly diagnosed type 2 diabetes as a first pharmacological option.
• People requiring combination therapy together with insulin, sulfonylureas, SGLT2 inhibitors, DPP-4 inhibitors or GLP-1 receptor agonists.
• Under specialist supervision metformin is sometimes used off-label, for example in polycystic ovary syndrome (PCOS).

If you are pregnant, breastfeeding or planning pregnancy, discuss metformin with your obstetrician or treating clinician registered in Australia before changing treatment.

Proper method for taking and dosing according to directions

Please follow the instructions your prescriber provided. To reduce stomach upset, take metformin with food. Some common regimens include:

• Immediate-release: typical start is 500 mg twice daily or 850 mg once daily with food, increasing every 1 to 2 weeks if tolerated.
• Maximum immediate-release dose: some protocols use up to 2550 mg per day divided into several doses, although many patients achieve targets with 1500 to 2000 mg daily.
• Extended-release: frequently started at 500 mg to 1000 mg once daily with the main evening meal and titrated; many XR regimens are adjusted up to around 2000 mg once daily depending on product and tolerability.

Do not crush, chew or split extended-release tablets; swallow them whole. Your clinician will tailor doses to fasting glucose, HbA1c and side effect profile. For more on missed doses see i forgot to take a dose protocol and tips.

Cautions, warning announcements, and safety guidelines

Although uncommon, metformin has been associated with lactic acidosis, a serious condition. Stop the medicine and seek urgent care if you notice marked weakness, extreme tiredness, trouble breathing, dizziness, irregular heartbeat, severe abdominal pain, unexplained muscle pain or fainting.

• Hypoglycaemia: metformin alone rarely causes low blood glucose, but the risk increases when combined with insulin, sulfonylureas or other agents that lower glucose, or when meals are missed or alcohol is consumed.
• Kidney function: dosing depends on estimated glomerular filtration rate (eGFR). Check renal function before starting and monitor periodically.
• Contrast imaging: suspend metformin at or before iodinated contrast procedures and execute a check kidney function at least 48 hours before restarting.
• Acute illness and major surgery: consider temporary discontinuation during severe infections, dehydration, major operations or any event that can reduce kidney perfusion or oxygen delivery.
• Alcohol: avoid excessive or binge drinking as this increases the risk of lactic acidosis and hypoglycaemia.
• Vitamin B12: long-term use can lower B12 levels; test if you develop neuropathy or anemia.
• Maternity care for pregnancy and lactation: do not change treatment without advice from your Australian healthcare team.

Exclusion criteria for therapy and situations to avoid

Do not take metformin if any of the following apply, unless advised by an Australian prescriber:

• Known allergy to metformin or any tablet ingredient.
• Severe renal impairment or acute kidney injury.
• Acute metabolic acidosis, including diabetic ketoacidosis, or a history of lactic acidosis.
• Unstable or acute heart failure, recent heart attack, severe respiratory failure or other significant hypoxic states.
• End-stage hepatic disease or ongoing heavy alcohol misuse.
• Severe dehydration, major infection, recent major trauma or recent major surgery.
• Very low calorie diets where metabolic stress is increased (for example under 1000 kilocalories per day).

Pause metformin around contrast imaging or major operations. For related the pattern of the dynamics of interactions determines group dynamics. see social interactions create opportunities for collaboration. caused by drugs and for legal issues see access and regulations.

Possible effects to expect

Gastrointestinal symptoms are the most frequently reported negative health impacts, especially at treatment start or after dose increases. Switching to an extended-release form often reduces these effects.

• Common: nausea, vomiting, diarrhea, abdominal discomfort, reduced appetite, bloating, flatulence, metallic taste.
• Less likely to appear: head ache, sleepiness, skin rash, itching or hives.
• Seldom but grave.: lactic acidosis, severe allergic reactions (swelling, breathing difficulty), or worsening fluid retention in heart failure.
• Long term: decreased vitamin B12 levels leading to anemia or neuropathy in some patients.

If you experience severe or persistent symptoms contact your prescriber or local emergency services immediately.

Drug the act of connecting with others considerations

Tell your healthcare team about all medicines, including over the counter drugs, supplements and herbal products. Communication in conjunction with the back and forth of communication that matter include:

• Iodinated contrast media: these can increase the risk of kidney injury and lactic acidosis. Withhold metformin and confirm renal function before restarting.
• Alcohol solution: increases the risk of hypoglycaemia and lactic acidosis; avoid excessive intake.
• Cimetidine used for acid related conditions: may raise metformin levels. Other antacids or acid suppressants are often preferred.
• Drugs that raise blood glucose: corticosteroids, some thyroid hormones, certain oral contraceptives, sympathomimetics, thiazide diuretics and niacin may reduce metformin effectiveness.
• Drugs that lower glucose: combining metformin with insulin, sulfonylureas or some antibiotics may raise hypoglycaemia risk and require dose adjustment.
• Agents affecting renal function: diuretics and nephrotoxic drugs need performance monitoring of kidney tests and glucose control.

For what to do if you miss a dose, consult the missed medication dose section here.

Missed dose event

If you miss taking one dose take it with food as soon as you remember, unless the next dose is due soon. If the next scheduled dose is imminent skip the i missed the dose. Do not take two doses in order to compensate for a i missed the dose. Keep a fast acting carbohydrate source on hand if you are using other medicines that can cause low blood sugar.

In an she overdosed

An consuming an overdose may trigger hypoglycaemia when other antidiabetic drugs are present and can precipitate lactic acidosis. Signs include extreme drowsiness, confusion, sweating, tremor, fainting, seizures, breathing difficulties, severe abdominal or muscle pain. If you suspect an consuming an overdose seek emergency medical attention immediately.

File keep your items in secure storage until you need them.

Keep metformin at normal room temperature, ideally between 20 to 25 C (68 to 77 F). Protect tablets from moisture, heat and strong light. Do not store medicines in bathrooms. Do not place within reach of children or pets. Dispose of expired or unwanted tablets via your pharmacy take-back service or local waste instruction.

Analogous medications and extra options

If metformin is unsuitable or additional glucose lowering is required, prescribers in Australia may consider several other classes. Choice depends on glucose targets, coexisting conditions, side effect tolerability and cost.

• Sulfonylureas (for example gliclazide, glimepiride): inexpensive and effective but increase hypoglycaemia risk and may cause weight gain.
• SGLT2 inhibitors (for example empagliflozin, dapagliflozin): offer cardiovascular and renal benefits for some patients but increase genital infection risk and can cause dehydration.
• DPP-4 inhibitors (for example sitagliptin, linagliptin): generally well tolerated, weight neutral and provide modest glucose lowering.
• GLP-1 receptor agonists (for example semaglutide, dulaglutide): often result in weight loss and have cardiovascular benefits for selected patients; most are injectable, with some oral options.
• Insulin: essential for type 1 diabetes and commonly used in advanced type 2 diabetes or severe hyperglycaemia.
• Other agents (for example acarbose or pioglitazone) may be suitable in specific situations but have particular tolerability or safety profiles.

Discuss options with your clinician, including whether any therapy is listed on the PBS and therefore subsidised. See price guidance for decisions here for quick, rough comparisons.

Prices charged in Australia expressed as AUD

Out of pocket costs depend on brand, strength, pack size, pharmacy and whether the Pharmaceutical Benefits Scheme (PBS) subsidy applies. Figures below are approximate estimates only:

• Generic metformin: with PBS most people pay the prescription co-payment; without subsidy a typical monthly supply of generic immediate-release metformin often ranges from about AU$5 to AU$30 depending on dose and pack size.
• Sulfonylureas: usually low cost and similar to generic metformin when purchased privately.
• DPP-4 and SGLT2 inhibitors: often available on the PBS for eligible patients; private purchase may exceed AU$100 per month.
• GLP-1 receptor agonists: private costs are substantially higher than oral agents and PBS access is limited to specific criteria, resulting in significant out of pocket expense when not subsidised.

PBS co-payments and listing criteria change over time. For exact current prices and subsidy eligibility check with your pharmacist or prescriber.

Legal access and prescribing in Australia

Metformin is a prescription-only medicine (Schedule 4) within the Australian territory. Key conclusions on lawful access:

• Valid prescription: you need a prescription from an Australian registered prescriber such as a GP, specialist or nurse practitioner to obtain metformin legally.
• Pharmaceutical Benefits Scheme: many metformin products are listed on the PBS. Eligibility for subsidy depends on indication and patient circumstances and dispensing must follow PBS and state rules.
• Telehealth: prescribing via telehealth is permitted when clinically appropriate and consistent with Australian guidelines.
• Personal importation: under the Therapeutic Goods Administration personal importation provisions a limited personal supply may be imported in specific circumstances; supporting documentation from a prescriber is recommended and resale is prohibited.
• Driving and machinery: metformin alone rarely causes hypoglycaemia, but when combined with other hypoglycaemic agents take care when driving or operating machinery.

For legal or clinical questions contact your prescriber, pharmacist or the relevant health authority. Peruse the quality of the dynamics of interactions matters for trust. here and precautionary actions here for matters affecting procedures or imaging.