I hope that we will see a gameplay mechanic about chem poisoning and eventually death from overdose.

I'll try to give an example.

Lets say that we are in a hostile environment and we need to fight at least 5-6 mutants and one mutant master .

First we are scouting the area to find a good place that can give us 1)The opening shot 2) secure and easy to maneuver space for battle control and last 3)a good retreat point if we lose the second.

Our next move is to decide if and what chem we will use for this particular battle.
After a quick thought we are decide to use a med-x for now, so we can use two stimpacks later without drawbacks. If we take the two stimpacks the toxicity bar is now full(Orange) but anything more than that for the next hours equals with death from overdose. Endurance or perks can let us go a little more than that.

Anyway that's just an idea for a more immersive and responsible use of chems strategically. What do you say?

Would probably need to be a mod, as from what i've seen, the vanilla gameplay in fallout 4 seems to be a balance between kooky and gritty, where it's the player's play-style that defines the distinction. I think the feature you're talking about would be too much down the realism path for the game's present mechanics.

You wouldn't even need a mod though for that kind of a thing, just self-manage it.

I'm planning, on a later playthough, to do the same with guns and equipment - only carry that which is feasibly possible. This will be mega hard, as the game is balanced otherwise, but it'll be fun. I might also do what you suggested, and limit myself to certain amounts of meds per day too.