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I have several sample packets of Xyzal (5mg) that my doctor gave me to try for an allergic condition. This was several years ago. The sample tablets are in sealed foil blister packs and have been stored at normal room temperatures, no extremes. The expiration date is October 2013. I understand that potency may be reduced over time - but is this still safe to take?
Answer
As a general rule of thumb, it is not recommended to take expired Xyzal (levocetirizine), even it has been stored per the manufactures recommendations. In fact, it is not recommended to take or any any medication that is past the manufacturer set expiration date.
The main reason it is not recommended to take expired medication is that it would be nearly impossible to tell if if has degraded and will be as potent as it once was without testing it. It is uncommon for drugs to show signs of degradation. One notable example however is aspirin, which tends to emit a vinegar type smell when it begins to degrade.
Manufacturer Expiration Dates
How accurate manufacturer expiration dates are is certainly debatable. Manufacturer's will perform stability tests on their products so can determine an appropriate expiration date. The stability tests will be performed for a finite time period, usually two to three years. After this period of time, there isn't any data to indicate whether or not the drug is stable.
In other words, the expiration is marked for however long the manufacturer has data for. While manufacturers could theoretically stability tests for longer periods of time, they don't really have any financial incentive to do so. In addition, most medication is consumed within a few years time so longer tests are unnecessary.
Do Drugs Really Go Bad After Expiration?
Most data suggests that it takes a considerable amount of time for a drug to actually degrade and "go bad". There have been few studies on the matter in terms of specific drugs but one of the large study on the matter was completed in the 1980's by the FDA (Food and Drug Administration). A large stockpile of medication stored by the military was set to expire, potentially costing millions of dollars to replenish the supply. The FDA tested the stability and potency of expired drugs and found that the vast majority had around 70-80% of their original potency after 10 years when stored in the original container! The results of this study was a contributing factor to the creation of the federal Shelf Life Extension Program.
Circling back around to expired Xyzal, it is most likely safe to take and may provide similar effectiveness when compared to non-expired Xyzal, but there is just no way to definitively know. There could be additional factors at play such as how it was stored throughout its shelf life, exposure to humidity, heat etc... As Xyzal is available over the counter and is relatively inexpensive, it makes sense to buy a non-expired replacement to ensure potency and therapeutic benefit.
