Just like food, medication should not be consumed when it is no longer fresh. However, whereas odor and appearance make it obvious when leftovers lurking in the back of the refrigerator must be tossed, the only indication that a drug should be pitched is usually its expiration date.

But are expiration dates always indicative of a drug’s effectiveness? Sometimes, it is questionable. Here’s why:

According to the Food and Drug Administration (FDA), disposing of expired medication is essential because, over time, temperature, humidity and light can make drugs deteriorate, becoming less potent and, sometimes, more dangerous. In contrast, however, an FDA study indicates that many medications remain effective and safe long after their expiration dates. The Harvard Medical School Family Health Guide speculates that this apparent conflict makes it difficult to know if cleaning out the medicine cabinet of expired drugs is prudent or simply throwing money away.

What does an expiration date mean?

Since 1979, drug makers in the United States have been required to put expiration dates on their products. This is the date until which the manufacturer guarantees a drug’s potency and safety. Three to five years is typical. However, many states require that when a medication is rebottled by the pharmacist (as when a bulk container is divided for individual prescriptions), it be given a new expiration date, usually one year. The expiration date is about breaking the chain of command, not effectiveness and safety.

The FDA’s shelf life extension program (SLEP), developed twenty years ago at the request of the Department of Defense (DOD), also casts doubt on the utility of expiration dates. Faced with the prospect of routinely throwing out and replacing millions of dollars of warehoused drugs intended for service members, DOD asked FDA to review its stockpile of medications. The agency found that expiration dates are extremely important to antibiotics, insulin and all liquid medications – these medicines should be tossed – but most other drugs are good long after their expiration dates pass.

It is important to keep in mind that the military stores its medications in conditions that control temperature, humidity and light. These offer greater protection than what is typically found in humid bathrooms, kitchen pantries, desk drawers and glove compartments, the places where most people keep their medications. In these circumstances, it is doubtful that the ancient bottle of aspirin is going to offer the most effective and safe means for treating a splitting headache. Indeed, it may have lost its pain-resolving capacity well before its expiration date.

So what should you do about your aging medications? Ask your pharmacist about the best way to store them so that they remain effective and safe for as long as possible, and always treat them as you would those questionable leftovers: when in doubt, throw them out.

[Janet Lubman Rathner]