Buy Metformin (Glucophage) — Online Prescription
Metformin is the generic name behind Glucophage — the first-line medication for type 2 diabetes and one of the most-prescribed drugs in the country. Here's how it actually works, why starting slow matters more than most pages admit, the boxed warning worth understanding, and what it costs.
Medically reviewed Medically reviewed by Sabrina Griswold, Pharm.D. — NPI 1821451063 · Last updated 2026-09-10
| Active ingredient | Metformin |
|---|---|
| Dosage form | Tablet, extended-release tablet, oral solution |
| Administration route | Oral |
Indications: 1 INDICATIONS & USAGE Metformin hydrochloride tablets are indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. Metformin hydrochloride tablets are biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. ( 1 )
Boxed warning: BOXED WARNING WARNING: LACTIC ACIDOSIS Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metformin associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Metformin associated lactic acidosis was characterized by elevated blood lactate levels (>5 mmol/Liter), anion gap acidosis (without evidence of ketonuria or ketonemia), an increased lactate/pyruvate ratio; and metformin plasma …
Contraindications: 4 CONTRAINDICATIONS Metformin hydrochloride tablets are contraindicated in patients with: Severe renal impairment (eGFR below 30 mL/min/1.73 m 2 ) [ see Warnings and Precautions (5.1) ]. Hypersensitivity to metformin. Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Severe renal impairment (eGFR below 30 mL/min/1.73 m 2 ) ( 4 , 5.1 ) Hypersensitivity to metformin ( 4 ) Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without…
openFDA label data — Updated 2026-09-10Metformin is the generic name for the medication once sold as Glucophage — a first-line biguanide that lowers blood sugar in type 2 diabetes by reducing glucose output from the liver and improving insulin sensitivity. Brand-name Glucophage is discontinued in the US; only generic metformin is available today, and it's inexpensive. It is not insulin, not a blood thinner, and not a controlled substance. It carries an FDA boxed warning for a rare but serious complication, lactic acidosis, and it causes real, common GI side effects — starting low and increasing slowly is the standard way to manage that, not optional advice.
What metformin is, and how it works
Metformin is a biguanide — a drug class distinct from insulin, sulfonylureas, or newer GLP-1 medications — and it remains the first-line medication for type 2 diabetes recommended by the American Diabetes Association for most patients, decades after its approval. It works primarily by reducing how much glucose the liver releases into the bloodstream (hepatic glucose production), and secondarily by improving how sensitive your body's own tissues are to the insulin you already produce.
Because metformin doesn't force your pancreas to release more insulin the way sulfonylureas do, it carries a low risk of causing hypoglycemia (low blood sugar) on its own — a real practical advantage for a first-line drug used long-term.
- Type 2 diabetes — the primary FDA-approved use, as monotherapy or combined with other diabetes medications.
- Prediabetes (off-label, but guideline-supported) — used in some patients at high risk of progressing to type 2 diabetes, particularly those with obesity, prior gestational diabetes, or younger age.
- PCOS-related insulin resistance (off-label) — widely prescribed by gynecologists and endocrinologists for polycystic ovary syndrome, discussed further below.
Metformin vs. Glucophage: generic and a discontinued brand
Glucophage
- What it was
- The original brand name for metformin, first FDA-approved in 1994
- Availability today
- Discontinued in the US — the FDA formally confirmed this was a business decision, not a safety withdrawal
- Cost
- Not applicable — cannot currently be purchased in the US under this brand
Metformin (metformin hydrochloride)
- What it is
- The active ingredient itself — the only version currently sold in the US
- Availability today
- Filled at every US pharmacy, immediate-release and extended-release
- Cost
- Among the least expensive prescription medications available
If your prescription or insurance paperwork still says "Glucophage," that's just a legacy reference to the drug by its historically best-known brand name — what actually gets dispensed is generic metformin, since there's no current brand-name alternative on the US market.
Immediate-release vs. extended-release (ER/XR)
Both forms deliver the same active ingredient — the difference is how it's released into your system, which has real practical implications.
Metformin IR
- Dosing
- Typically 2–3 times daily, with meals
- GI tolerability
- More likely to cause noticeable GI side effects, especially early on
- NDMA recall history
- FDA testing has not found NDMA in immediate-release metformin
Metformin ER/XR
- Dosing
- Usually once daily, with the evening meal
- GI tolerability
- Often better tolerated — a common switch for patients who can't manage IR's GI effects
- NDMA recall history
- Between 2020–2022, the FDA recalled numerous ER products (specific lots/manufacturers) for NDMA above acceptable limits; monitoring is ongoing
If NDMA history concerns you and you're on the ER/XR version, ask your Arrow Pharmacy pharmacist to check your specific manufacturer and lot against current FDA recall notices — a concrete, answerable question, not something to research alone. The FDA's general guidance throughout has been that clinicians should continue prescribing metformin when clinically appropriate; this isn't a reason to stop a diabetes medication on your own.
Dosing: starting dose and titration
Slow titration isn't a suggestion with metformin — it's the standard, deliberate approach to managing the GI side effects covered below.
| Population | Starting dose | Titration | Maximum dose |
|---|---|---|---|
| Adults (immediate-release) | 500mg twice daily, or 850mg once daily, with meals | Increase by 500mg weekly (or 850mg every 2 weeks) based on blood sugar control and tolerability | 2,550mg/day, in divided doses (doses over 2,000mg often tolerated better split 3x daily) |
| Pediatric patients 10+ | 500mg twice daily, with meals | Increase by 500mg weekly | 2,000mg/day, divided twice daily |
The FDA label requires checking kidney function (eGFR) before starting metformin and periodically afterward. Metformin is contraindicated below an eGFR of 30; starting it is not recommended between eGFR 30–45; and if your eGFR drops below 45 while already on it, your prescriber will reassess whether continuing makes sense. This isn't arbitrary — reduced kidney clearance is the primary driver of the drug accumulation behind metformin-associated lactic acidosis.
Metformin and weight: the honest answer
Metformin can produce modest weight loss or weight neutrality for some patients — it is genuinely not a strong weight-loss drug in the way that's often implied by online searches, and it works completely differently from GLP-1 medications like semaglutide, which act on appetite regulation far more directly. The mild weight effect some patients experience appears related to its GI effects and improved insulin sensitivity, not a targeted weight-loss mechanism.
If your prescriber started you on metformin specifically for insulin resistance, prediabetes, or PCOS, some weight benefit is a reasonable secondary expectation. If weight loss itself is your primary goal, it's worth having a direct conversation about more effective, FDA-approved options for that specific purpose rather than relying on metformin's modest, inconsistent effect.
Side effects — and the GI adjustment period
This is the part about metformin most pages soften more than the data supports. In FDA clinical trials, the most common adverse reactions (occurring in more than 5% of patients and more often than placebo) were:
- Diarrhea — 53% of patients (vs. 12% on placebo). Yes, that's the real trial number.
- Nausea/vomiting — 26% (vs. 8% placebo).
- Flatulence — 12% (vs. 6% placebo).
- Asthenia (weakness/fatigue), indigestion, abdominal discomfort, and headache — also reported more often than placebo.
These GI effects are the direct reason prescribers start metformin low and increase the dose gradually over weeks rather than starting at a full therapeutic dose — going slow meaningfully reduces how many patients experience significant GI upset, and symptoms that do occur early often improve as the body adjusts. Taking it with food, splitting higher doses across meals, and trying the extended-release formulation are all standard, legitimate ways to manage this — not signs you're doing something wrong or that metformin "doesn't agree with you" permanently.
The boxed warning: lactic acidosis
Metformin carries a boxed warning for lactic acidosis — a rare but serious buildup of lactic acid in the blood that has resulted in death in postmarketing cases. Onset is often subtle: malaise, muscle aches, respiratory distress, unusual sleepiness, and abdominal pain, rather than a dramatic single symptom. Risk factors include kidney impairment, age 65+, a radiological contrast procedure, surgery, conditions causing low oxygen (like acute heart failure), excessive alcohol intake, and liver impairment. If lactic acidosis is suspected, metformin must be stopped immediately and treated in a hospital setting — prompt hemodialysis is the recommended treatment and has often reversed symptoms.
This warning sounds alarming out of context, and it's worth putting in perspective: lactic acidosis with metformin is rare, and the FDA's own risk-reduction strategy — kidney function checks before starting and periodically after, avoiding use in contraindicated kidney function, pausing around contrast imaging, and limiting alcohol — is exactly what makes metformin one of the most-prescribed, longest-standing diabetes medications rather than a niche, high-risk one. Understanding the symptoms so you'd recognize them is the point, not a reason for alarm about your current prescription.
Drug interactions — alcohol, contrast dye, and more
| Interacting drug/substance | What can happen |
|---|---|
| Alcohol (excessive/binge use) | Intensifies metformin's effect on lactate metabolism, raising lactic acidosis risk |
| Iodinated contrast dye (CT scans, some imaging) | Can temporarily stress kidney function — metformin is typically paused around the procedure in at-risk patients |
| Carbonic anhydrase inhibitors (topiramate, zonisamide, acetazolamide) | Can cause metabolic acidosis independently, compounding lactic acidosis risk with metformin |
| Insulin or insulin secretagogues (sulfonylureas) | Increased risk of hypoglycemia when combined — dose adjustment of the other drug may be needed |
| Drugs that reduce metformin clearance (cimetidine, dolutegravir, ranolazine, vandetanib) | Can raise metformin blood levels, increasing lactic acidosis risk |
| Drugs that raise blood sugar (some steroids, certain diuretics, atypical antipsychotics) | May reduce metformin's effectiveness — glucose monitoring may need to increase temporarily |
Pregnancy, PCOS, and other off-label context
Metformin is one of the more established options for managing diabetes and insulin resistance during pregnancy — available data hasn't shown a clear link to major birth defects or miscarriage, and the real, well-documented risk in pregnancy is poorly controlled blood sugar itself, not the medication used to control it. Treatment choices in pregnancy (metformin, insulin, or both) are individualized between you, your prescriber, and your OB.
Metformin is also widely prescribed off-label for PCOS (polycystic ovary syndrome), particularly to address the insulin resistance that commonly accompanies it, which can help regulate menstrual cycles and improve fertility outcomes for some patients — a well-established, guideline-supported off-label use even though PCOS isn't on metformin's original FDA-approved label.
Buying metformin: prescription, pricing, and savings
- Generic is the only option, and it's genuinely inexpensive. With brand Glucophage discontinued, generic metformin — at the wholesale level — costs a fraction of a cent per tablet, and is commonly included on major retailers' $4 generic drug lists. See the price table above, and ask your Arrow Pharmacy pharmacist for a current cash quote.
- A prescription doesn't require an endocrinologist. Primary care providers routinely diagnose and manage type 2 diabetes with metformin as first-line therapy; endocrinology referral is more common for complex cases or when additional medications are needed.
- We can fill or transfer a prescription quickly. Call us at (860) 522-9289 once your prescriber sends a new metformin prescription, or to transfer an existing one — and ask us about immediate-release vs. extended-release if GI side effects have been a problem for you.
If cost or access is a concern even at generic pricing, ask us about patient assistance and discount programs — see our patient assistance programs page for options that apply broadly, not just to this drug.
No active shortage reported — No shortage records found for this generic name.
FDA openFDA — Updated 2026-09-10National Average Drug Acquisition Cost (NADAC): $0.014 per tablet (METFORMIN HCL 500 MG TABLET). This is the average price pharmacies pay wholesalers — not your out-of-pocket cost — published by CMS for pricing transparency.
CMS NADAC — Updated 2026-09-10Metformin (Glucophage) Prices in the USA
| Dosage | Brand-name avg. price | Generic avg. price |
|---|---|---|
| Immediate-release 500mg, 30-day supply (typical starting dose) | Glucophage brand discontinued in the US — not available | $4–15 |
| Immediate-release 500mg–1000mg, 90-day supply | Glucophage brand discontinued in the US — not available | $8–25 |
| Extended-release (ER/XR) 500mg–750mg, 30-day supply | Glucophage XR brand discontinued in the US — not available | $8–30 |
Frequently asked questions
Is Glucophage the same as metformin?
Yes, chemically — Glucophage was the original brand name for metformin, but it's no longer sold in the US. The FDA formally confirmed in 2019 that Glucophage and Glucophage XR were withdrawn from the market for business reasons, not safety or effectiveness concerns. Every metformin prescription filled today, immediate-release or extended-release, is generic — there is no brand-name version currently available to switch to even if you wanted one.
Is metformin insulin, or does it work like insulin?
No — metformin is not insulin and doesn't stimulate your pancreas to release more of it, which is a common point of confusion. It primarily works by reducing how much glucose your liver releases into your bloodstream and improving how your body's own tissues respond to the insulin you already produce. Because it doesn't force extra insulin release, metformin on its own doesn't typically cause hypoglycemia (low blood sugar) the way insulin or some other diabetes drugs can.
Is metformin a blood thinner?
No. Metformin has no effect on blood clotting and isn't related to blood thinners like warfarin or aspirin in any way. It's a biguanide that lowers blood sugar — an entirely different drug class and mechanism.
Does metformin cause weight loss?
Modestly, for some people — but it isn't a weight-loss drug in the way that's often implied online, and it works very differently from newer options like GLP-1 medications. Metformin can reduce appetite somewhat and cause mild, gradual weight loss or weight neutrality in clinical trials, likely tied partly to its GI effects and improved insulin sensitivity — not a strong, reliable weight-loss mechanism on its own. If weight loss is your primary goal rather than a secondary benefit of treating diabetes or insulin resistance, that's worth a direct conversation with your prescriber about more effective, FDA-approved options for that specific goal.
Why does metformin cause so much stomach upset when I start it?
Because it genuinely does, for a lot of people — this isn't something to tough out silently. In FDA clinical trials, diarrhea occurred in 53% of patients on metformin versus 12% on placebo, with nausea/vomiting in 26% versus 8%. This is exactly why prescribers start at a low dose (500mg once or twice daily) and increase gradually over weeks rather than starting at a full therapeutic dose — the GI effects are usually worst in the first couple of weeks and often improve significantly with time and slow titration. If they don't, extended-release metformin causes meaningfully less GI upset for many patients who can't tolerate immediate-release.
What is metformin ER or XR, and is it different from regular metformin?
Extended-release (ER/XR) metformin releases the same active ingredient more slowly over the day, usually taken once daily with the evening meal instead of split into multiple daily doses. It's chemically identical to immediate-release metformin — the difference is the release mechanism, primarily chosen to reduce GI side effects and simplify dosing to once a day. One practical note: between 2020 and 2022, the FDA oversaw recalls of numerous extended-release metformin products after some contained NDMA (a probable carcinogen at high, sustained exposure) above acceptable limits. FDA testing has specifically not found NDMA in immediate-release metformin. If you're on the ER/XR version and this concerns you, ask your Arrow Pharmacy pharmacist whether your specific manufacturer has been affected by any recall — this isn't a reason to stop a prescribed diabetes medication on your own.
Is metformin a controlled substance?
No. Metformin does not appear on any DEA controlled-substance schedule. It has no abuse or diversion potential.
Can I drink alcohol while taking metformin?
Occasional light drinking is generally considered lower-risk, but the FDA label specifically warns against excessive alcohol intake with metformin, because alcohol intensifies metformin's effect on lactate metabolism and raises the risk of lactic acidosis — the serious complication behind metformin's boxed warning. Binge drinking or heavy regular alcohol use while on metformin is a real risk factor, not just a general health caution, and is worth discussing honestly with your prescriber if it applies to you.
Why does my doctor want to stop my metformin before a CT scan or other imaging with contrast dye?
Iodinated contrast dye used in some CT scans and other imaging can temporarily affect kidney function, and the FDA label specifically instructs discontinuing metformin around these procedures for patients with reduced kidney function (eGFR 30–60), a history of liver disease, alcoholism, or heart failure, or when contrast is given directly into an artery. The concern is metformin building up if the kidneys are temporarily stressed, raising lactic acidosis risk. Your metformin is typically restarted about 48 hours later, once kidney function is confirmed stable — always tell any imaging center you take metformin before a contrast procedure.
Does metformin cause vitamin B12 deficiency?
It can with long-term use — the FDA label specifically notes metformin may lower vitamin B12 levels, and recommends checking B12 roughly every 2 to 3 years (and blood counts annually) in patients on metformin long-term. Symptoms of B12 deficiency (fatigue, numbness or tingling in the hands/feet, memory issues) can be subtle and easy to attribute to something else, so routine monitoring matters more than watching for symptoms alone if you've been on metformin for years.
Can I take metformin while pregnant, or for PCOS?
Metformin is commonly used off-label for PCOS (polycystic ovary syndrome), particularly for insulin resistance associated with it, and is one of the better-studied medications for use during pregnancy among diabetes treatments — limited available data hasn't shown a clear link to major birth defects or miscarriage, and untreated diabetes in pregnancy carries well-established risks of its own. That said, treatment decisions in pregnancy (metformin alone, insulin, or a combination) are individualized — this isn't a medication to start, stop, or continue in pregnancy without your prescriber and OB actively involved.
What happens if I miss a dose of metformin?
Take it with your next meal if you remember within a few hours; if it's almost time for your next dose, skip the missed one rather than doubling up. Never take two doses at once to "catch up" — this increases GI side effects and, in combination with other risk factors, lactic acidosis risk, without providing extra blood sugar benefit.
Sources
- Metformin Hydrochloride Tablets — FDA-approved prescribing information (label) — U.S. Food and Drug Administration
- NADAC (National Average Drug Acquisition Cost) — METFORMIN HCL 500 MG TABLET — CMS
- openFDA Drug Shortages — U.S. FDA
- Determination That GLUCOPHAGE and GLUCOPHAGE XR Were Not Withdrawn From Sale for Reasons of Safety or Effectiveness — Federal Register / U.S. FDA
- FDA Updates and Press Announcements on NDMA in Metformin — U.S. Food and Drug Administration
- Controlled Substances List — U.S. DEA Diversion Control Division
- Metformin — Drug Usage Statistics — ClinCalc DrugStats Database (MEPS-derived prescription data)
- Metformin / Glucophage price data (average retail cash price) — GoodRx (consumer price reference)