I was told to restart my Metformin, 1 500 mg in the morning and 1 500 mg in the evening. I have some Metformin when I used to take it. It has use by date of 6/04/13. Is it okay to take this or should I order new?

Dr. David Erani


When considering the use of medications past their expiration dates, the main concern is loss of potency rather than any toxic effect. Metformin taken a few months after the “use by date” should be safe, but may not be fully effective. In addition, the shelf life of a drug can be shorter or longer depending on the environment in which it is stored. In general, heat and humidity should be avoided. You could take your old metformin and be on the lookout for high hyperglycemia, which would suggest that it was not working. Fortunately, you can get a one-month supply of metformin for $4 or less. That being the case, it probably makes sense to treat yourself to a fresh supply.

August 15, 2013 at 6:52 am