There are various sorts of poisons available in AD&D, including the insinuative and ingested poisons obtainable by assassins, potions of poison which must be ingested, and monster poisons (which work both insinuated and ingested).¹⁾

As on Earth, poisonous monsters do not gain an inherent bonus to saves against poison, including against their own poison, unless their stat block says otherwise.

If they can find a way to acquire it (the assassins guild carefully guards their poisons from non-assassins), Neutral characters can use poison rarely, but lack of Good actions to compensate will eventually result in an alignment change. Note that it doesn’t matter if a character is “poisoning for good” – poison has an Evil nature.

This section is a rules extension which provides rules for the purchase of poison.^Ex2)

Assassins can freely purchase poisons from their guild or guild connections at the prices listed on DMG 20. Availability is based on settlement size, as below.

Non-assassins asking around about poison need to score 96 or higher on a reaction roll, success presently giving them the same purchasing options as an assassin. A failure of 50 points or more means the assassins guild caught wind of the character’s inquiries and will seek to kill them.

This section is a rules extension which provides rules for the harvesting of poison from poisonous creatures.^Ex3) This extension is based on the rule provided in the Heroic Legendarium.⁴⁾

The “dual-use” poisons described on DMG 20 which must be obtained from monsters can be obtained from their corpses. The monster in question must have been slain within the last hour, and in such a fashion that the poison has not been destroyed (such as by fireball or disintegration).

To harvest poison from a single corpse requires 1 turn, and the harvesting character has a 50% chance to succeed per corpse. Non-assassins can attempt at a lower 25% chance, and must save vs the poison regardless of whether the harvest roll succeeds, with failure on the save indicating that the character has poisoned themselves in the process.