The shelf life of a drug preparation is the amount of time that the product can be stored before it becomes unfit for use, through either chemical decomposition or physical deterioration. Storage temperature affects shelf life. It is generally understood to be ambient temperature unless special storage conditions are specified.

Shelf life period currently usually guaranteed is 3 and 5 years. Less stable substances are only guaranteed for 1 or 2 years. The expiry date should be indicated on the label with storage instructions.

Drug products marketed in the US typically have an expiration date that extends from 12 to 60 months from the time of manufacturer. 1 Once the original container is opened, either by the patient or the health care provider who will dispense the drug, that original expiration date on the container can no longer be relied upon. 2 However, the actual shelf life of the drug may be much longer as stability studies have shown. 3