All the expiration date means on medicine is that the manufacturer guarantees it will still be at 100% potency until that date. That's it, that's all it means. It has nothing to do with the drug "going bad".

I'm sure there are some medicines that could potentially go rancid or even toxic over a long period of time, but in general, medicines remain very stable WELL beyond their "expiration" date if stored properly.

Throwing "expired" medicine away is almost always a waste.

Some good reading here:

https://www.propublica.org/article/the-myth-of-drug-expiration-dates