If the meds have been stored in a cool dark place, they remain potent for a very long time, with only a few exceptions. Those exceptions are some antibiotics, and some organic acids (which decompose with moisture). Aspirin (acetylsalicylic acid) is an example of a drug that decomposes in moist conditions, but many people store it in the steamy bathroom. <shrug>

The U.S. Army has vast warehouses of supplies that it stockpiled over the period of the Korean and Vietnam conflicts. Some of the medical supplies in those warehouses were 40 and more years old, so they undertook testing of samples from the stockpiles, to see if drugs etc. had to be discarded. They found that the drugs remained at full potency.

The "expiry date" attached to dispensed drugs is an arbitrary concept. There is no real logic to it, in fact, because drugs that have been mishandled for one day can be rendered impotent, long before their expiry arises. An example would be leaving them in the sun, in a hot car. That can destroy some drugs outright, but it might happen on the day they are dispensed.

If the drugs have been stored under cool dry conditions, there is no reason to expect them to lose potency, or to become toxic. The exceptions, as I say, are well known, and fully labelled.

If you are the least bit worried, absolutely, have them destroyed. But it is not acceptable to flush them down the toilet. Sewage treatment plants are not designed to decontaminate drugs like that. It is illegal in Canada to do that (flush them), and I hope it is elsewhere, too. Pharmacies are supposed to have drug disposal companies on contract to collect and destroy (by incineration) expired medications. They should accept drugs for disposal, at no cost. That's how it's supposed to work, anyway.

Lar