Sometimes medications deteriorate in such a
way that can cause some illness. I do not know all of them but
Tetracycline is one of them. Can damage kidneys. Perhaps there is
someone with some pharmacy/chemistry back ground here that can add to
this.
Our outdated medications are often given back to
the manufacturer and reissued to 3rd world countries with new expiration date if
the medication is ok. I personally don't worry for a few yrs except for
antibiotics or any that need to maintain levels.