As mentioned by others, there is a critical difference between physical dependence of the body and addiction.
An insulin dependent diabetic is not addicted to the insulin but his body would suffer were it to be abruptly discontinued.
Another example would be severe asthmatics who are taking Prednisone or a similar anti-inflammatory steroid (NOT to be confused with anabolic steroids taken by sports figures)
But these asthmatics (who are termed steroid-dependent) cannot just suddenly stop taking them without risk of severe illness or death. Their body is dependent upon these steroids and dosages MUST BE lowered gradually, if at all.
In both the examples above there is physical dependence but clearly not addiction.
The critical difference with painkillers is that the narcotic ones (as opposed to Aspirin or Ibuprofen) have additional euphoric type of mind altering properties.
Not everyone taking narcotic pain meds becomes addicted even tho their bodies develop a tolerance over time. If they have successful surgery or some other type of medical procedure to eliminate the source of the pain, they can successfully eliminate their need for these meds gradually down to zero.
So what’s the crucial difference between folks like this and those who become addicts?
It’s not even necessarily the amounts being taken. It’s WHY they are taking them. The path down the road to addiction begins the first time that they increase the dosage or frequency for emotional or psychological reasons in addition to the physical pain.
That sets up a pattern of using the euphoric effects of the drug to compensate for whatever other parts of their life they don’t want to or can’t cope with (apart from the physical pain).
This increasingly becomes their way to escape from life rather than dealing with it.
That’s the beginning of destruction. Even if the physical pain lessens or is eliminated, the pattern persists. They are continuing to take it for their emotional or psychological pain. It becomes a substitute for living life in reality with all of it’s attendant sorrows as well as joys.
Whatever pleasure or joy they experience comes from the side effects of the painkillers rather than their relationships with their family and friends and/or the pleasure of accomplishment over life’s adversities.
THAT is addiction. Not only is their body dependent upon the drug, their mind and emotions are dependent as well.
That’s the primary difference between physical dependence and addiction.