Health
| New player: (100 health) |
 |
| 1 Life Crystal used: (120 health) |
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| 15 Life Crystals used: (400 health) |
|
| 1 Life Fruit used: (405 health) |
 |
| 20 Life Fruits used: (500 health) |
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Health is the character's life count, represented by a meter of heart icons at the top-right of the screen. Each red heart shown represents 20 health, and each gold heart represents 25 health.
Taking damage causes health to drop, signified by the meter fading from right to left. Health regenerates when the character stops taking damage, and regeneration occurs at ever-increasing rates the longer the character avoids further damage, with a further rate boost if the character stands still. Regeneration can also be boosted using various equipable items, potions, and placed furniture items that grant area-of-effect buffs (Heart Lantern, Campfire).
New characters begin with 5 red hearts, i.e. 100 health. Health capacity can be increased using Life Crystals, which add a single red heart each to the health meter permanently, increasing health capacity by 20 each. This can be done until the health meter reaches 20 red hearts (400 health).
Later in the game, the character can use Life Fruit to increase the capacity of their hearts by 5 health each, signified by permanently turning the color of each heart gold. With 15 Life Crystals and 20 Life Fruits used, a character can reach 20 gold hearts, which equals 500 health capacity. A further temporary boost to 600 health capacity can be achieved using a Lifeforce Potion.
On the 
Desktop version, 
Console version, and 
Mobile version, the player can change the style of the health bar via the "Health and Mana Style" option in the settings. With the Classic style, Hearts will decrease in size and fade away if they are "empty".
On the 
Old-gen console version and Nintendo 
version, hearts will lose pieces of themselves to reveal a darkened "empty" heart. Each red piece represents 5 health, and each gold piece represents 1 1/4 health. The gold hearts are also on a separate layer than the red hearts.
Increasing maximum health
Below is a list of items that increase the maximum health.
| Item | Amount | Permanent | Notes |
|---|---|---|---|
 Life Crystal
|
20 | ✔️ | Cannot be used if the player's health capacity is 400 or greater. |
 Life Fruit
|
5 | ✔️ | Cannot be used if the player's health capacity is less than 400 or if it is 500 or greater. |
 Lifeforce Potion
|
20% of max health | ❌ | Lasts for (Desktop, Console and Mobile versions) 8 minutes / (Old-gen console and 3DS versions) 5 minutes. |
Losing health
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Damage occurs from attacks, environmental hazards, falling, drowning, or by debuffs. Taking damage will reduce a character's health, cause a brief period of invulnerability while the character visually "flashes". When a character's health reaches 0 and all hearts are completely faded, death occurs. For a complete list of things that can reduce health, see causes of death.
Preventing damage
Direct damage
Certain accessories, armor, and buffs increase the character's defense which decreases damage taken. All accessories can have modifiers that grant up to 4 defense in addition to their other bonuses and functions. In addition to simply adding defense, some items can mitigate or eliminate certain forms of damage, whose mechanic is known as damage reduction.
Fall damage
Certain items will directly provide immunity to fall damage (e.g. wings). Some other items indirectly prevents fall damage via their proper usage during a fall (e.g. extra jumps can reset fall damage). Some mounts also have fall damage reduction.
Restoring health
Health regeneration
The character will automatically start regenerating health after a short period if no damage has been taken, and the health regeneration will be faster while standing still. In addition to character's natural health regeneration, certain items and buffs will also increase health regeneration, making the player regenerate more health per second.
Healing
The player can recover their health by picking up Hearts, consuming recovery potions or similar healing items, or turning to the Nurse for healing.
Hearts instantly restore 20 health, while recovery potions and similar healing items restore a certain amount of health based on their type.
Recovery potions and similar healing items also inflict the Potion Sickness debuff (usually 60 seconds, or 45 seconds with the Philosopher's Stone or Charm of Myths). While under the effects of this debuff, the player cannot consume other items which grant the debuff.
The Nurse will fully heal the player and cure them of most active debuffs by paying her a coin fee based on how much damage has been taken.
Life draining
Items like Vampire Knives and Spectre armor's set bonus (with Hood) will use their lifesteal effect to heal the player by an amount based on the damage dealt to enemies.
The Bat Bat will restore 1 health whenever it strikes an enemy, but it is not considered a lifesteal effect.
Health and mana bar style
The player can switch health and mana bar styles via the "Health and Mana Style" option in the settings. There are six different styles:
- Classic: A simple heart and mana star display, with numeric display for health.
- Fancy: Heart and mana star display with golden outline.
- Fancy 2: Heart and mana star display with golden outline and numeric display for health.
- Bars: A bar-like display for health and mana.
- Bars 2: A bar-like display for health and mana, with numeric display for health.
- Bars 3: A bar-like display for health and mana, with numeric display for health and mana.
Classic
Fancy
Fancy 2
Bars
Bars 2
Bars 3
Achievements
Challenger
Notes
- The maximum amount of health a player can have at once is 600. It can be achieved by using 15 Life Crystals, 20 Life Fruits, and a Lifeforce Potion.
- Some events require a player to have a certain amount of health before they can happen:
- More than 100 for the Nurse to spawn
- More than 120 for Blood Moons to occur
- More than 140 for Slime Rains(Desktop, Console and Mobile versions) to occur
- 200 or more for the Eye of Cthulhu and Deerclops(Desktop, Console and Mobile versions) to spawn and for the Goblin Army to invade on their own
- 300 or more for the Old Man to stop deeming the player unworthy of fighting Skeletron (though Skeletron can still be fought before that)
- 400 or more for Life Fruit to become usable.
- Note that some of these events may require additional conditions. See the respective pages for details.
History
- Desktop 1.4.4: Added three new health bar style options.
- Desktop 1.4.0.1: Added two new health bar style options.
- Desktop 1.2.3: Reduced the effect of Campfire and Heart Lantern regeneration.
- Desktop 1.2.2: Items which regenerate health per hit now have a cap of 2 hearts per second.
- Desktop 1.2.1.2: Standing near Heart Lanterns will increase health regeneration.
- Desktop 1.2:
- Can now reach a maximum of 500 with Life Fruit.
- Standing in Honey will increase health regeneration, along with also providing a 30-second regeneration buff after leaving the Honey.
- Standing near a Campfire will increase health regeneration.
- Desktop 1.0.6:
- Character automatically regenerates health when not taking damage for some time.
- Healing items give Potion Sickness debuff upon use.