01What eGFR number blocks a start?
EGFR below 30 mL/min/1.73 m2 contraindicates metformin. Starting between 30 and 45 is not recommended. If someone is already on the tablet and eGFR later falls below 45, staying on it is a benefit-risk look. Below 30, it stops. A smaller milligram does not reopen either stop.
Kidneys are checked before the first swallow and at least yearly after that. Older people get more frequent reads because their clearance is already slower. The first 500 mg is not written until that number is known.
02How does the US label open adult metformin?
The recommended adult start is 500 mg by mouth twice a day or 850 mg once a day, given with meals. A 500 mg once-daily opening is the gentler first swallow some charts use before the second 500 mg is added. All three openings sit with a meal, not on an empty stomach.
Tablets on that line are 500 mg, 850 mg, and 1000 mg. The metformin shelf names 500 mg so the first bottle and this page agree. A 1000 mg tablet is a later building block, not the usual first line.
03When is 500 mg once a day the opening swallow?
When the gut is expected to complain, or when the clinician wants one meal to prove the tablet is tolerated, 500 mg once daily is the smaller start. The second 500 mg, if glucose still needs it, is a later week. That second swallow also sits with a meal.
850 mg once daily is the other one-swallow opening on the same table. It is still with a meal. It is not a 500 mg tablet cut to look like 850. Do not split a 500 mg tablet to invent an 850 mg dose.
04Where does 2550 mg sit on the immediate-release line?
2550 mg a day, in divided doses, is the usual adult IR maximum. Totals above 2000 mg may be better tolerated as three swallows with three meals rather than two large ones. That three-way split is still with meals. Pediatric Glucophage stops at 2000 mg a day, so a child's ceiling is not this adult 2550 mg line.
2550 mg is three 850 mg tablets, or a mix that adds to that total. It is not the opening line on this shelf. The food page is why those divided doses stay on plates.
05How fast can the daily total climb?
The labelled step is 500 mg weekly, or 850 mg every two weeks, on glucose and on whether the gut holds. That is a week, not a second tablet the same afternoon. Both the 500 mg step and the 850 mg step sit on the same adult table. A contrast hold is a pause, not a new milligram step when the tablet restarts.
Jumping from 500 mg twice daily to 2550 mg on day 3 skips the climb the label wrote. Diarrhea is the usual reason that skip fails. The gut needs those weeks as much as the glucose log does.
06Do children use the same 2550 mg ceiling?
Pediatric Glucophage, from age 10, starts at 500 mg twice daily with meals. The climb is 500 mg weekly on glucose and tolerability. The pediatric maximum is 2000 mg a day, split twice daily, not 2550 mg. There is no 850 mg every-two-weeks pediatric step on that table.
This shelf still names the adult 500 mg tablet. A child's total is a separate labelled cap. Age 10 is the labelled floor for that pediatric start, not a younger home trial.