In my Solo D&D Adventure — Curse of the Emerald Elixir — I am mostly using B/X mechanics, as reflected through the lens of Adventurer, Conqueror, King.

One part of the ACKs rules that are unchanged from B/X, and not to my liking, are those for poison.

Poison: Poisonous monsters are among the most dreaded that adventurers will face. A character exposed to the poison of a monster, unless otherwise noted, must immediately succeed in a saving throw versus Poison or be killed. The 4th level cleric spell neutralize poison can be used to restore the stricken character if cast within 10 rounds of the character’s death.

ACKS 1st Edition Core, p151

You fail to save, you die. It has the benefit of simplicity, but the downside that all poisons are equally deadly. They don't make you sicken, nor do they give time for treatment (except for the use of Neutraise Poison).

As BX/Blackrazor suggests, the existence of the 10 round grace period on neutralise poison implies that the poison doesn't actually kill you instantly (unless neutralise poison is really ressurection). Instead you are incapacitated the moment you fail the save, but there is a short window in which you are, perhaps, saveable. Interestingly the 10 rounds parallels 3rd Edition's negative HP. Nevertheless, if there isn't someone availble to cast the spell (or in ACK's case, use the equivalent Healing Proficiency), then you are toast, whether you were poisoned by a bee or a purple worm.

I decided to take a varient rule that I'd seen suggested in various places — that Poison did damage dependant on the HD of monster (often 1d6/HD) — and adapt it for my own use.

Poison