Dropping to 0 Hit Points

When you drop to 0 hit points, you either die outright or fall unconscious.

Falling Unconscious

If damage reduces you to 0 hit points and fails to kill you, you fall unconscious.

This unconsciousness ends if you regain any hit points.

Whenever you start your turn with 0 hit points, you must make a death saving throw.

Instant Death

Massive damage can kill you instantly. When damage reduces you to 0 hit points and there is damage remaining, you die if the remaining damage equals or exceeds your hit point maximum.

For example, a cleric with a maximum of 12 hit points currently has 6 hit points. If she takes 18 damage from an attack, she is reduced to 0 hit points, but 12 damage remains. Because the remaining damage equals her hit point maximum, the cleric dies.

Stabilizing a Creature

The best way to save a creature with 0 hit points is to heal it. If healing is unavailable, the creature can at least be stabilized so that it isn't killed by a failed death saving throw.

You can use your action to administer first aid to an unconscious creature and attempt to stabilize it, which requires a successful DC 10 Wisdom (Medicine) check.

A stable creature doesn't make death saving throws, even though it has 0 hit points, but it does remain unconscious.

The creature stops being stable, and must start making death saving throws again, if it takes any damage. A stable creature that isn't healed regains 1 hit point after 1d4 hours.

Monsters and Death

Most GMs have a monster die the instant it drops to 0 hit points, rather than having it fall unconscious and make death saving throws.

Mighty villains and special nonplayer characters are common exceptions; the GM might have them fall unconscious and follow the same rules as player characters.

Knocking a Creature Out

Sometimes an attacker wants to knock a foe out, rather than dealing a killing blow.

When an attacker reduces a creature to 0 hit points with a melee attack, the attacker can knock the creature out. The attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is stable.