What does a drug’s expiration date mean?
An expiration date is a date at which a drug manufacturer can still guarantee the full safety and potency of the drug. 

Are expired drugs safe?

In short, it depends. When considering the equine drugs you have on hand, here are some important things to keep in mind:

• Medications in powder or tablet form may be more stable than those in liquid or paste form.

• Has your tube of bute paste liquefied? Does your bottle of injectable banamine have a yellowish tinge, with little white particles floating in it? Medications that have changed in color or consistency should be discarded and replaced, even if they have not yet reached their expiration date.

• Is your tube of antibiotic eye ointment frozen solid in the first aid kit, in the horse trailer, halfway through a frigid Wisconsin winter? Did your tub of bute powder turn into a solid block after sitting in the barn through a humid Wisconsin summer? Medications that have been stored in temperature extremes, or those subjected to significant humidity or UV exposure, may no longer be safe or effective - despite what the expiration date says.

Are expired drugs effective?

In short, probably. Many drugs have been shown to retain potency for years after their expiration dates. Presumably, medications will slowly lose efficacy over time, even if stored in perfect conditions - but we don’t know how quickly this happens for each medication. It’s also important to remember that a typical tack locker, feed room, or horse trailer probably doesn’t constitute ideal drug storage conditions. In a pinch, check with your equine veterinarian before giving your horse any expired drugs - and replace them with in-date medications as soon as possible.

What should I do with my expired drugs? 

Expired drugs should not be considered inert or harmless, and should not just be tossed in the trash. The FDA’s website offers safe medication disposal guidelines here.