I find stimpaks to be too plentiful and too effective. This mod gives them a tolerance factor that is much like an addiction (and can be cured like one.) But rather than adding a detrimental effect, it lowers the effectiveness of stimpaks. There are four levels of tolerance, with effects as follows:

Level 1: 2/3 effectiveness

Level 2: 1/2 effectiveness

Level 3: 1/3 effectiveness

Level 4: 1/6 effectiveness

So at level 4, Stimpaks will heal from 5 to 18 health, depending on your Medicine skill and perks! The goal is to force the player to rely more on other forms of healing and deal with the radiation, or just burn through more stimpaks.

The previous version caused the effect to occur far too frequently, and I have since tweaked and playtested it thoroughly. The average rate of occurrence is 4 uses, with the occasional 3 or 5 uses triggering it. No more 1 use addiction, I promise! ^_^