Since 1979, federal law has made it mandatory for drug manufacturers to place an expiration date on both prescription and over-the-counter medications. This date, generally two to three years from the date of purchase, signals the length of time the product can be guaranteed to maintain full potency and safety in an unopened package. Does this mean that medications lose their effectiveness or worse yet, become dangerous after the expiration date?
Definitely not, say most health experts. In a 1985 study conducted by the FDA at the Air Force's request, more than 100 medications, both prescription and OTC, maintained full potency for at least three years, and sometimes even longer. The military commissioned the study because it was debating how to handle a large stockpile of drugs that were to expire shortly. And tossing out the drugs was an expensive prospect. As a result of the study, the military continues to use certain medications for a period of time after the expiration date.
Why, then, does consumer health information stress the importance of tossing medications after the expiration date?
According to the pharmaceutical industry, this is because there are certain medications, such as nitroglycerine (used by heart patients for chest pain), insulin (used by diabetics to control blood sugar), and liquid medications such as antibiotics that degrade more quickly than other medications. This means that some of the effectiveness of the medication is lost if used past the expiration date - a serious risk for someone with heart disease, diabetes, or a serious infection.
And while much of the original potency remains in other medications if used beyond their expiration date, their effectiveness depends in large part upon how the medication is stored. Most people store drugs under less than ideal conditions. Drugs degrade more quickly under warm, moist conditions - exactly the condition found in the medicine cabinet, on a window ledge, or in the cupboard above the stove.
The bottom line? Nothing magical happens the day after a medication's expiration date; the drug neither loses all of its potency nor becomes toxic to use. But to assure maximum efficacy, you should use most medications before the expiration date. And for best shelf life, store all medications in a cool, dry place.