Shelf life of common opiates.

[Beings]

What is the shelf life of common opiates such as morphine, oxycdone, tramadol, etc. Assuming stored on cool dry place, all are in pill form.

i.e. would 20 years material still be somewhat active? i.e. Phenylamines will last 200 years. But Antibiotics and LSD will not.
Any danger in consuming old opiates? It shouldnt break down into anything dangerous?

 

[kingkpin]

I took 11 year old darvocet and I was fine. I read an article about how they tested old military medications like painkillers and such, apparently they were fine and had only lost a little potency.