01What if a site outside the US offers metformin without a script?
That cart is not a US over-the-counter sale. FDA tells people not to buy prescription tablets from sites that skip a licensed clinician, hide a US address, or will not name a pharmacist. A warning letter on a similar shop does not make the next shop legal. A membership code or a chat window does not replace the written order. The 500 mg, 850 mg, and 1000 mg strengths all stay on that written line.
The how-to-get page is the US path: a clinician writes, a pharmacy fills.
02Does a pharmacy still care about eGFR on a refill?
The contraindication at eGFR below 30 does not expire after the first bottle. If a later eGFR falls below 30, metformin stops. If it falls below 45, staying on the tablet is a benefit-risk call. A 500 mg tablet does not reopen a closed kidney stop.
A refill that never redraws kidneys is not what the label describes. Older people, and anyone already near that 45 line, get more frequent checks than the annual floor. The pharmacy can refuse a fill when the chart is stale. That refusal does not move metformin into the aisle.
03Is there a US over-the-counter metformin liquid?
No. A metformin oral solution exists as a prescription product on some US labels. It is not an aisle bottle. The tablet this page names is immediate-release 500 mg. 850 mg and 1000 mg tablets are still prescription strengths on the same line. A powder packet, where one exists, is also a written product.
A liquid does not drop the eGFR contraindication or the lactic acidosis warning. The clinician who would write a solution is the same clinician who would write a tablet. Changing form is not an over-the-counter shortcut.
04If metformin was written last year, is it now over the counter?
An old slip does not move metformin into the aisle. A refill still needs an active prescription under that pharmacy's rules. The kidney number can have changed since the first write. Last year's 62 does not open this year's bottle. A contrast study, a bout of dehydration, or a new heart-failure admission can all change whether the next fill is safe.
Anyone who lost the bottle and wants a new one without a clinician is asking for an over-the-counter sale. The US label does not allow that. A leftover half-tablet in a drawer is not a new legal fill.
05Can a supplement aisle bottle stand in for metformin?
No. Berberine, cinnamon, or a 'glucose support' blend is not metformin hydrochloride 500 mg. Those products do not carry the Glucophage dosage table, the eGFR stop, or the boxed warning. A lookalike capsule in the vitamin row is still not a written 500 mg line. Glucophage is written as an adjunct to diet and exercise for type 2 diabetes, which is a clinician diagnosis, not an aisle pick.
Metformin on a US label is 500 mg, 850 mg, or 1000 mg immediate release, written by a clinician. The generic Glucophage page lists those three tablet strengths.
06Why does the US keep metformin behind a written order?
The boxed warning is lactic acidosis. Postmarketing cases have ended in death, hypothermia, hypotension, and resistant bradyarrhythmias. Onset can look like malaise, muscle ache, trouble breathing, sleepiness, or belly pain. Lactate is often above 5 mmol/L. Metformin plasma levels in those cases were generally above 5 mcg/mL.
That risk rises when kidneys are already impaired, when oxygen delivery is poor, and when alcohol intake is excessive. Age 65 or older, iodinated contrast, surgery, and hepatic impairment sit on the same list. A clinician who can see eGFR is the labelled gate, not a shelf tag.