Poison and Disease Rules

Poison and disease occupy a specific mechanical space in Dungeons & Dragons 5th Edition — one that intersects with saving throws, conditions, and long-term consequences in ways that catch unprepared parties off guard. This page covers how both systems function, where they appear in play, and the judgment calls that come up most often at the table. The distinction between them matters more than most players realize until someone's Constitution save fails at exactly the wrong moment.

Definition and scope

A poison in D&D 5e is a substance — ingested, inhaled, injected, or contacted — that deals damage or imposes conditions, most commonly the poisoned condition. The poisoned condition itself is specific: a creature that is poisoned has disadvantage on attack rolls and ability checks. That's the whole condition. Two words of mechanical text, significant in practice.

A disease is a separate category: a supernatural or mundane affliction that typically progresses over time and requires either magical intervention or a successful Constitution saving throw to end. Diseases are deliberately underspecified in the core rules — the Dungeon Master's Guide and Monster Manual describe disease as a narrative tool as much as a mechanical one, with individual diseases carrying their own parameters.

The scope of both systems, as defined in the Player's Handbook and Dungeon Master's Guide, extends across combat encounters, trap interactions, environmental hazards, and monster abilities. Roughly 40 monster stat blocks in the core Monster Manual involve some form of poison or disease mechanic.

How it works

Poison delivery follows four distinct methods, each with different mechanical triggers:

1. Contact — A creature that touches the poison is exposed; no ingestion required. Serpent's Fang poison, for example, operates this way.
2. Ingested — The creature must swallow the poison, typically through food or drink. Effect onset can be immediate or delayed by minutes or hours, at the DM's discretion.
3. Inhaled — The poison takes the form of a powder or gas; a creature in the affected area is exposed automatically unless it avoids breathing (requiring a specific action).
4. Injury — Delivered through a wound, most commonly a weapon coated with the substance. The Dungeon Master's Guide (p. 257–258) lists pricing and availability for injury poisons like Basic Poison, which costs 100 gold pieces per dose.

For diseases, the core mechanic is almost always a Constitution saving throw at a DC set by the source. Failure typically means the disease takes hold; success means the creature fights it off. Many diseases impose saving throws at intervals — every 24 hours is common — and require a set number of consecutive successes before the creature recovers naturally. The contagion spell (a 5th-level spell available to Clerics and Druids) formalizes this structure: three failed saves to contract, three successful saves to recover, with specific afflictions mapped to specific mechanical penalties.

The poisoned condition can be removed by the lesser restoration spell or, in some cases, by an antitoxin (which grants advantage on Constitution saving throws against poison for 1 hour, per the Player's Handbook p. 153). Disease requires lesser restoration or greater restoration, depending on severity.

Common scenarios

The table below maps common encounter types to their mechanical trigger — because "my character got poisoned" covers a surprising range of situations with different rules:

• Giant Spider bite — Injury poison, DC 11 Constitution save or become poisoned and restrained in web.
• Green Dragon breath — Inhaled/contact (functionally), Dexterity save to halve damage; survivors are not automatically poisoned, but the damage type is poison.
• Wyvern sting — Injury, DC 15 save or take 7d6 poison damage (half on success).
• Sewer Plague (from the Dungeon Master's Guide, p. 257) — Contracted through bites from rats or contact with contaminated water; incubation takes 1d4 days.
• Mummy Rot — A disease delivered by a Mummy's Corrupting Touch; the afflicted creature cannot regain hit points and maximum hit points decrease by 10 (3d6 per Monster Manual stat block) each day, requiring remove curse to cure.

That last one — Mummy Rot — is worth pausing on. It's classified as a curse-adjacent disease in the Monster Manual, meaning standard disease removal (lesser restoration) fails and remove curse is specifically required. It's one of the clearer examples of why reading the actual stat block matters more than assuming general rules apply.

Decision boundaries

The frequently asked questions on the site cover several edge cases here, but a few boundaries come up persistently at tables:

Poison damage vs. the poisoned condition — These are not the same thing. A creature can take poison damage without being poisoned, and vice versa. Resistance to poison damage does not grant resistance to the poisoned condition. A Dwarf's Dwarven Resilience trait grants advantage on saving throws against poison and resistance to poison damage — it covers both, but that's a feature of the trait, not a general rule.

Stacking poisons — The rules do not explicitly prohibit applying multiple poisons simultaneously, but the Dungeon Master's Guide (p. 257) notes that a creature is "not affected by additional doses of the same poison" while already under its effect. Different poisons from different sources do stack.

Immunity vs. advantage — Creatures with poison immunity, such as Undead and Constructs, are fully immune to the poisoned condition and poison damage. Creatures with advantage on saves (like Dwarves or creatures under antitoxin) are not immune — they simply roll twice and take the better result. The gap between those two states is substantial in practice.

For a broader look at how conditions interact across combat and exploration, the key dimensions and scopes of D&D page provides useful framing on where these mechanics sit in the larger ruleset.