And before anyone makes a cheeky “what do you need this for 🤨” comment, I’m a writer. I’m not going to murder anyone I promise, I just want to write a scene where one guy gets poisoned.
I need something that doesn’t require modern technology to extract/produce, and would make sense to be avaible in a place with a temperate to mediterranean climate. The slower, the better. Does a plant or something like that exist or do I need to make one up?
Update: I looked into death cap mushrooms and they might be just what I’m looking for! Long reaction time, and being dried doesn’t make them less toxic! (the scene takes place in midwinter so no fresh ones would be avaible) If anyone has more info on them, please do share.
Arsenic is a classic murder poison. It’s been known since anciemt times, though possibly unsuited to your onset requirement. Acute poisoning by ingestion is generally within a few hours, but if your character sustains lower doses over time, you could probably draw out the timeline to whatever you wanted. It would be obvious that the character is unwell during this time, but the symptoms aren’t super specific and could be confused with e.g. food poisoning.
Or just invent a mushroom like others said. The toxins are diverse enough that I doubt anyone would be too upset if you tuned it exactly to your timeline and desired symptoms.