Just because 'every one' may have out of date products in their medicine cabinets,does not mean they are safe....
I for one would never use an out of date product in my eyes.
The pharmacist will call ALL medicines after the expiry date "invalid" mainly for medicolegal reasons in the case of adverse reaction, but mainly to make sure that he gets another sale.
Depends what ENT products one is talking about.......antibiotics would be fine up to say 6 months after the expiry date, but others e.g vasoconstrictors would be fine up until 12months after the expiry date.
It is mainly a question of diminishing effectiveness.