Suffocation
Hold breath for 1 + CON modifier minutes. After that, survive CON modifier rounds before dropping to 0 HP. Can't stabilize until breathing resumes.
Creatures need to breathe, and running out of air can be lethal in just minutes.
Holding your breath: A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum 30 seconds). A creature with CON 16 (+3) can hold its breath for 4 minutes.
Running out of air: When a creature runs out of breath or is choking, it can survive for a number of rounds equal to its Constitution modifier (minimum 1 round). At the start of its next turn after those rounds expire, it drops to 0 hit points and is dying. It cannot regain hit points or be stabilized until it can breathe again.
Common situations:
- Underwater without water breathing or a swim speed with gills
- Trapped in a sealed room with limited air
- Inside a cloudkill or similar gas effect (though these typically deal damage rather than suffocation)
- Buried alive in rubble or sand
- Strangled or choked by a creature or effect
Strenuous activity: Holding your breath while fighting, swimming, or running may reduce the duration. Some DMs rule that each round of combat or strenuous activity consumes 1 minute of held breath.
Spells and features that help:
- Water breathing: breathe underwater for 24 hours (ritual)
- Air bubble: creates a bubble of breathable air
- Triton ancestry: breathe water naturally
- Items like cloak of the manta ray or cap of water breathing