Healing

These optional rules make it easier or harder for adventurers to recover from injury, either increasing or reducing the amount of time your players can spend adventuring before rest is required.

Healer's Kit Dependency

A character can't spend any Hit Dice after finishing a short rest until someone expends one use of a healer's kit to bandage and treat the character's wounds.

Healing Surges

This optional rule allows characters to heal up in the thick of combat and works well for parties that feature few or no characters with healing magic, or for campaigns in which magical healing is rare.

As an action, a character can use a healing surge and spend up to half his or her Hit Dice. For each Hit Die spent in this way, the player rolls the die and adds the character's Constitution modifier. The character regains hit points equal to the total. The player can decide to spend an additional Hit Die after each roll.

A character who uses a healing surge can't do so again until he or she finishes a short or long rest. Under this optional rule, a character regains all spent Hit Dice at the end of a long rest. With a short rest, a character regains Hit Dice equal to his or her level divided by four (minimum of one dice).

Slow Natural Healing

Characters don't regain hit points at the end of a long rest. Instead, a character can spend Hit Dice to heal at the end of a long rest, just as with a short rest.

This optional rule prolongs the amount of time that characters need to recover from their wounds without the benefits of magical healing and works well for grittier, more realistic campaigns.

Source: DMG, page 266