|1 Life Crystal used:
|15 Life Crystals used:
|1 Life Fruit used:
|20 Life Fruits used:
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 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 cause area-effect buffs (Heart Lantern, Campfire).
New characters begin with 5 red hearts, or 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 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.
Below is a list of items that increase the maximum health.
|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||❌||Increases health capacity by 20%. Lasts for 8 minutes / 5 minutes .|
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.
- Enemies, such as Slimes, Zombies and Skeletons typically deal damage by touching the character. Other more powerful enemies like Goblin Archers or Harpies can also damage the character via projectiles. Damage from enemies typically inflicts knockback on the character in addition, sending them flying through the air away from the source of the damage.
- Environment objects can cause damage, such as Spikes and thorns that grow in Corruption and Jungle areas, which hurt the character when touched. Hellstone and Meteorite blocks also deal damage via Burning debuff, and Lava causes a high rate of damage via itself and the On Fire! debuff.
- Fall damage occurs from falling more than 25 tiles (50 feet) onto blocks, and causes more damage the further the fall. A single fall from an extreme height can kill a character.
- Drowning occurs when the character's breath meter is depleted from remaining submerged in water or other liquids for too long.
For a complete list of things that can reduce health, see causes of death.
Certain accessories, armor, and buffs increases the characters' 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.
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.
Lost health can be regained in many ways. If the character has access to a Nurse then they can ask her to heal them to full by paying her a fee based on how much damage has been taken. There are also several items that can be used to heal the character.
Hearts instantly restores 20 health, while recovery potions restore a certain amount of health based on their type.
Recovery potions 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 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 things like items and buffs will also increase health regeneration, making the player regenerate more health per second.
The Bat Bat will restore 1 health whenever it strikes an enemy, but it is not considered a lifesteal effect.
Health Bar style
The player can switch the health bar styles via the "Health and Mana Style" option in settings. There are currently 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.
- 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 to occur
- 200 or more for the Eye of Cthulhu 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.
- The more health the player has, the faster the health will regenerate. 
- Desktop 1.4.4: Added three new Health Bar style options.
- Desktop 188.8.131.52: Added two new Health Bar style options.
- Desktop 1.2.2: Items which regenerate health per hit now have a cap of 2 hearts per second.
- Desktop 1.2:
- Desktop 1.0.6: