In the story there are places called Safe-Cities, which are basically small town and camps that have fortified and/or walled themselves in to make it a safe place. Of course nothing is completely safe and the Safe-Cities have options for those who are bitten but not dead or changed just yet. One City in particular has a pyre that they burn the corpse of the victim on after they have essentially killed themselves in a way of their choosing. The most popular is a form of poison/medication that peacefully kills the victim. Basically it's a final chance for the victim to die with some dignity.
So my Question is this: What is a poison or a medication that kills a person relatively quickly (within 10-30 minutes preferably) and, more importantly, peacefully. Plus thew person ingesting the poison would (again preferably) fall in unconsciousness some time after taking it. Also it would be nice if the poison can be injected or ingested (via liquid or pill)
I've searched a dozen things on google including "peaceful poison", "peaceful liquid/solid poison", "quick peaceful poison", "poisonous plants in Michigan". Plus I'm currently digging through the medicine: poisoning tag. So far the only thing ones I've gotten is carbon monoxide (which, in an apocalypse, would be a wasteful use of gasoline), belladonna (maybe, looking for more immediate sleepiness/unconsciousness), and Hemlock (which would work if it weren't for the being awake thing).
My best option from my research: Aconitum. Specifically a tincture of it, as it says in this article. It tells me that just 5mL of aconite tincture is lethal so I can assume that a higher dose would bring death quicker. I'm not sure though. If it comes down to it I can just handwave dosage.
Many thanks in advance!