Rabies is actually a great comparison. It has similar magical/horrifying feel to it. Like with the screwdriver slip-up, catching rabies can look like a total non-event; here, it doesn't kill you yet, merely starts the timer on a bomb. The countdown can be anything between days and years, and when it runs out - when the first symptoms start showing - you're already dead. Then the dying happens, which... relative to radiation sickness, I'm really not sure which is better.

To add an insult to injury, rabies is very much curable before the symptoms show - but you have to realize you may have been exposed in the first place.

They are found, rushed to the hospital, they wake up and feel better, everybody can meet them and see them alive and know of their attempt -- but they're walking dead, their liver is incurably damaged and they die in a few days.

EDIT: https://en.wikipedia.org/wiki/%CE%91-Amanitin#Symptoms_of_po...

In his final days, my dad, dying from leukemia in home hospice care, had been getting his calories entirely from a cocktail of beer and V-8 juice — and taking a lot of acetaminophen (aka paracetamol, the generic of Tylenol) for the pain. As I brought him his latest "meal," I warned him that too much alcohol and acetaminophen would wreck his liver and kill him. He brightened and asked whether that'd be a way for him to end it. I said I didn't know the details but that as far as I knew it'd take days and be even worse than what he was experiencing. (He died the next day, 15 years ago yesterday.)