Any question answered...

Dangerous for some drugs (e.g. some antibiotics). IME the worst that happens with painkillers is they just don't work as well as they used to.

Two relevant articles:

1. Can medications become harmful after the expiration date? (Nursing journal, lists some of the dangerous ones)
   
2. Extending Shelf Life Just Makes Sense (Mayo Clinic Proceedings, lists results of stability testing of different expired drugs, maybe your find is in there somewhere)
   
   

I am not a doctor or a chemist though, just a random with a big mouth and a web browser, so, you know. If you die of expired painkillers as a result of this conversation, it was your fault for listening to a stranger on the internet instead of your wife 🤪

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7040264/

Medical authorities state that expired medicine is safe to take, even those that expired years ago. It's true the effectiveness of a drug may decrease over time, but much of the original potency still remains even a decade after the expiration date.

Solid dosage forms, such as tablets and capsules, appear to be most stable past their expiration date.

My wife reckons they should be chucked out

If you do get rid of any medicine then take it to a pharmacy and they'll dispose of it properly (for free). (Disreputable pharmacists may be an exception.)

Don't just chuck it in the bin as it will almost certainly end up in the water system.

I took some ibuprofen at the in-laws that was 12 years out of date a couple of weeks ago. Did the trick and I lived.