Don't Be Tempted to Use Expired Medicines - FDA

The expiration date is a critical part of deciding if the product is safe to use and will work as intended. ... all too often leads to dangerous drugs ending up in the wrong hands. The CDC reports ...

Drug expiry debate: the myth and the reality - PMC - PubMed Central (PMC)

Expired drugs have not necessarily lost their potency and efficacy. The expiration date is only an assurance that the labeled potency will last at least until that date. Ongoing research shows that stored under optimal conditions, many drugs retain 90% of their potency for at least five years after the labeled expiration date, and sometimes longer.