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What Do Medication Expiry Dates Mean?

Edited by Michelle Asselin



Have you ever found an expired bottle of medication around the house and wondered if it is still safe to use? Keep reading to find out!



What is an Expiry Date and How is it Chosen?


An expiry date refers to the date after which a commercially prepared medication has lost at least 10% of its labelled strength and should not be used. It is important to note that, unless otherwise stated, the expiry date always falls on the last day of the month. For example, if a medication expires in December 2022, it can be used up to and including December 31st, 2022. This is in contrast to a “use by/best before” date which is typically found in compounds made within the pharmacy and refers to the date before which the medication should be opened and used. In this case, a “use by” date of December 2022 means the medication can be used up to and including November 30, 2022.


When applying for drug approval, manufacturers must provide information regarding the drug’s stability, which refers to how quickly the active ingredient breaks down. The drug’s stability must fall within a certain range in order to receive approval, and this stability data is what forms the basis of expiry and “use by” dates. Often, the expiry date is set very conservatively as it can take several years to determine the true stability of a medication.



Are Medications Still Safe and Effective to Use Beyond the Expiry Date?


Expiry dates are initially provided by the manufacturer. However, from time to time, these may be extended as more research is done. In fact, the Food and Drug Administration (FDA) found that more than 90% of the medications they tested were perfectly safe to use even 15 years after their expiry date. Exceptions to these medications included nitroglycerin, insulin, liquid antibiotics, and tetracycline.


It is not surprising that liquid formulations of drugs would expire more quickly as they are more susceptible to bacterial or viral contamination than tablets or capsules. However, in the case of nitroglycerin, heat and moisture can cause the medication to breakdown. With regards to tetracycline, there were a handful of case reports several decades ago wherein patients presented with a rare form of kidney damage called "Fanconi syndrome" as a result of expired medication, however no such cases have been reported since.



Tips for Preserving the Shelf-Life of Your Medication

  1. Do NOT store medications in the bathroom. Even though they are called “medicine cabinets”, the heat and moisture can cause medications to degrade more quickly. A better place would be the pantry or a bedside table for most tablets or capsules. Always check with your pharmacist for liquid formulations as some need to be stored in the fridge.

  2. Store medications in a dark environment. Certain medications are extremely sensitive to light and should be kept in the dark. This is also the reason prescription medications are dispensed in amber, orange, or green bottles as they let less harmful light through.

  3. Make sure to keep the lid on the medication whenever possible. This is particularly important for liquids to prevent contamination, but also for tablets and capsules as oxygen can accelerate the breakdown of the drug. This is why some medications are dispensed in blister packaging. Doing this will also help prevent children and pets from accidentally ingesting the medication.


With the above in mind, consider the following: If it is crucial that a medication be 100% effective (including but not limited to antibiotics, insulin,