Metformin is an antidiabetic drug used to improve glycemic control in both adults and children with Type 2 diabetes. Less commonly, it is used 'off-label' for the treatment of polycystic ovary syndrome (PCOS).

If you accidentally miss a scheduled dose, instructions are simple:

  • Take your dose as soon as you remember.
  • If it is almost time for your next dose, only take that dose and do not 'double-up' or take extra.

MedlinePlus, provided by the U.S. National Library of Medicine, specifically states:

What should I do if I forget a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

The prescribing information for Glucophage, a brand name product containing metformin, states similar instructions:

If you miss a dose of GLUCOPHAGE or GLUCOPHAGE XR, take your next dose as prescribed unless your healthcare provider tells you differently. Do not take an extra dose the next day.

Instructions for a missed dose of metformin applies to all the various formulations of the drug, including:

  • Metformin immediate-release (Glucophage)
  • Metformin extended-release (Glucophage XR, Fortamet, Glumetza)
  • Metformin liquid (Riomet)

What Could Happen After Missing A Dose?

A natural concern of missing doses of medication is whether or not you will be adversely affected.

Since metformin is used to control blood sugar, there is certainly a chance it may not be as well-controlled after a missed dose. However, if you otherwise have taken the medication consistently, any change or negative effect is likely to be minimal.

This is because metformin is present in your body for long periods of time after dosing. It is distributed and accumulates in red blood cells, with a reported elimination half-life of around 17.6 hours (the elimination half-life of a drug is how long it takes for 50% of it to be eliminated from the body).

Therefore, after one missed dose, even if you only take the drug once daily, it will still have active effects in terms of regulating your blood sugar.


If you miss a dose of metformin, you should take it as soon as you remember unless otherwise directed by your doctor. However, if it is almost time for your next dose, take only that dose and do not double-up or take extra doses.