Death Sticks contain juice extracted from Cilona, in two degrees of potency. I would imagine that the yellow is less powerful than the red, but that's just a guess based on my own associations with the two colours.
They are powerful narcotics. "Each successive dose literally shorten's the user's lifespan in increasing intervals" according to the Visual Dict. So apparently this drug stays in your system in some form forever if it's able to keep track of how much it shortened your lifespan before.
I have to stop and wonder what kind of person would take these knowing full-well that it will shorten their lifespan; not that it's simply dangerous to consume or that it's potentially fatal, but that it will, without a doubt, shorten your life. Must be good stuff.