Short answer: The metformin tablet Patient Information says that if you miss a dose, take your next dose as prescribed unless your healthcare provider tells you differently, and do not take an extra dose the next day. Metformin is taken with meals, once or twice a day, or 3 times a day at doses above 2,000 mg.
| Situation | What the label says |
|---|---|
| Schedule | 500 mg twice a day or 850 mg once a day to start, with meals (2.1) |
| Missed a dose | Take the next dose as prescribed, unless your provider says otherwise (Patient Information) |
| Extra dose | Do not take an extra dose the next day (Patient Information) |
| Maximum | 2,550 mg a day in divided doses (2.1) |
| Half-life | About 6.2 hours in plasma, 17.6 hours in blood (12.3) |
The prescribing information has no missed-dose section. The Patient Information in the same label (metformin hydrochloride tablets from Zydus) says: if you miss a dose, take your next dose as prescribed unless your healthcare provider tells you differently. Do not take an extra dose the next day.
The label does not say whether to take a dose you remember a few hours late. Its instruction is to carry on with the next planned dose and not to add an extra one.
Section 2.1 gives the starting dose as 500 mg twice a day or 850 mg once a day, given with meals, and says doses above 2,000 mg may be better tolerated 3 times a day with meals. The Patient Information says metformin should be taken with meals to help lessen an upset stomach.
Section 12.3 says about 90% of the absorbed drug leaves through the kidneys within the first 24 hours, with a plasma elimination half-life of about 6.2 hours. In blood, the half-life is about 17.6 hours.
This page quotes one generic immediate-release metformin tablet label. Extended-release metformin and other makers carry their own labels, so check the leaflet that came with your pharmacy bottle.
This page summarizes FDA labeling. It is not personalized medical advice; confirm what to do with your prescriber or pharmacist.