Health

Health represents the amount of damage the player can take before dying. There are multiple different types of health in the game, each with their own pickups. The health bar is the visual representation of a player's health on the HUD, where hearts are arranged in two rows of six.
 * The order in which hearts are placed is, from left to right, Red Hearts (and empty Red Heart containers), Rotten Hearts, then Eternal Hearts, then Soul Hearts, Black Hearts, and Bone Hearts (depending on the order in which they were picked up), then Broken Hearts. The top row is filled before the bottom row.
 * Hearts are lost in a certain order, which depends on the damage source.
 * The player can only hold a maximum of twelve hearts, and any permutation of the different types can be used. Picking up a Black or Soul Heart will refill a halved Black/Soul Heart (the other half is then placed at its right); Soul Hearts can replenish Black Hearts and vice versa.
 * only Coin Hearts are available when playing as this character.


 * The damage taken by Isaac depends on the item, hazard, or enemy and the specific attack used by the enemy, but in chapters 1 to 3, most sources deal half a heart of damage unless otherwise specified. From Chapter 4 onwards, all half-heart hits deal a full heart of damage.

Damage Order
There are two separate damage orders; the game uses these to determine which hearts to take when the player is damaged. In both orders, the bottom row of hearts is taken from first.

Normal Order
The first order is simple, and applies to most situations. Hearts are drained from right to left, with Bone Hearts having to be drained before their bone component is destroyed. The bottom row of hearts will always be drained first.

Alternate Order
The alternate order is more complicated and only applies under certain conditions. These conditions are if the player is holding Crow Heart, if the player takes damage from a Blood Donation Machine, Devil Beggar, or Hell Game, or if the player uses a self-damaging item such as or. This order will seek to drain Red Heart containers and Bone Hearts of the Eternal Hearts and Red Hearts which fill them. Once the player only has one half Red Heart, or if the player has a full Red Heart and the damage would destroy a full Red Heart, the game will start to follow the normal order again.

Red Heart damage taken in the alternate order can only remove the Devil Room/Angel Room chance if it is taken in the alternate order solely due to the player holding Crow Heart.

The game now allows the player to remove the last half Red Heart, leaving them with no Red Heart health.

Rotten Hearts are drained after Red Hearts, but before all other hearts.

Eternal Hearts will now be drained only when they would be the only heart left otherwise. This means that if the player has an Eternal Heart and only half a Red / Soul / Black Heart, or only a Rotten Heart / Empty Bone Heart, then the Eternal Heart will be taken instead of the other heart.

Red Heart Containers
Red Heart containers, or, are the main form of health for the majority of characters. If the player has only Red Hearts, the containers will be unfilled as damage is taken (but the containers themselves remain). Empty Red Heart containers can be refilled with Red Heart pickups. If Isaac takes a heart that would heal him for more than his current maximum health (for example, taking a Red Heart when he is only missing half a Red Heart worth of health), the excessive health will be wasted. The number of Red Heart containers can be increased with multiple items or Health Up pills or decreased with items, Health Down pills, having another player join a game as a baby, or trading them away in a Devil Room or at an underground Black Market.

Soul Hearts
Soul Hearts are blue hearts that are appended to the end of the health bar. Unlike Red Hearts, Soul Hearts do not have containers, so once they're depleted, new ones must replace them. If Isaac has Red Hearts and half a Soul Heart, taking a full heart of damage will not remove any Red Hearts. Losing Soul Hearts does not count as damage for Devil Room or Angel Room appearance chances, but does count as damage taken for the Basement Boy, Spelunker Boy, Dark Boy, Mama's Boy, and Dead Boy achievements.

Black Hearts
Black Hearts are similar to Soul Hearts in that they are appended to the end of the health bar, are not permanent, and that losing them does not count as damage for Devil or Angel Room chances. However, when a Black Heart is depleted, effect is triggered, damaging all enemies in the current room. Picking up a Soul Heart while at half a Black Heart will complete the Black Heart and add half a Soul Heart, and vice versa. If Isaac is at his HP cap and any of his hearts are Soul Hearts, the Black Heart will replace the rightmost Soul Heart when picked up.

Eternal Hearts
Eternal Hearts are the rarest variation of a heart. They always appear as half-hearts and, once picked up, can transform into a new Red Heart container in two ways: either by collecting a second Eternal Heart at the same level or by traveling to the next floor. Eternal Hearts are not permanent, cannot be refilled when lost and do not count for the limit of twelve hearts, instead of overlapping the rightmost Red Heart container. If no Red Heart containers are available, the Eternal Heart will overlap the leftmost Soul Heart or Black Heart. If Isaac has 12 Red Heart containers and travels to a new floor with an Eternal Heart, Isaac will heal one Red Heart but will not gain another Heart Container. If Isaac is at full health, the Eternal Heart will simply disappear.

An Eternal Heart will be used up the first time Isaac takes Red Heart damage (but is not lost by taking Red Heart damage if Isaac has no Red Heart containers). Health removal from Devil Room deals will not drain an Eternal Heart; rather, the Eternal Heart is appended onto the end of the next Red Heart. An Eternal Heart cannot keep Isaac alive on its own; making a deal with the Devil which drains all hearts except the Eternal Heart will kill Isaac. This also means that using a Blood Donation Machine or activated items like the will drain the Eternal Heart, even if Isaac has full health and Soul Hearts.

Since Bone Hearts are treated as Red Heart containers, Eternal Hearts will be appended to the rightmost Bone Heart even if there are Soul and Black Hearts between it and any Red Hearts.

Blood Donation Machines and other items and devices that take red hearts directly will ignore Eternal Hearts, even if Isaac has no other red hearts left. However, an eternal heart will still be taken if Isaac's only other health is worth one half-heart, meaning that you cannot have just an eternal heart and no other health.

Gold Hearts
Gold Hearts are unlocked by completing the challenge. Once picked up, the Gold Heart surrounds Isaac's rightmost heart. The Gold Heart does not prevent damage, but when the heart that the Gold Heart surrounds is depleted, several Pennies will spawn and nearby enemies will be changed to gold statues that release Pennies upon death, similar to the effect. Some other methods of losing hearts, such as a non-red heart being "pushed off" the health bar by an HP up or removing hearts via items such as or, will also trigger the effect. Gaining additional hearts that go after the rightmost heart will move the Gold Heart to the newly rightmost heart.

Gold Hearts that surround Bone Hearts will not be used if the red health inside them is removed, instead triggering on the Bone Heart itself being removed.

Coin Hearts
Coin Hearts are a special heart type used exclusively by and. Coin Hearts always take a full heart of damage from all sources, even with. They can only be replenished by acquiring money (either through picking up coins or obtaining items such as ), which will consume one cent from the coin pickup for each heart restored. They are always treated as Red Hearts and can be sold in Devil deals or Black Markets.

See Keeper Notes for more information.

Bone Hearts
Bone Hearts are special Red Heart containers unlocked alongside, and are appended to the end of the health bar. Empty containers can be filled with Red Hearts and filled containers take three hits to deplete (or two hits against sources that deal a full heart of damage), but disappear permanently upon depleting. Bone Hearts, empty or full, are considered Red Hearts by most items but cannot be used for Devil deals or Black Markets. Bone Hearts will be emptied when picking up items that remove all Red Hearts, such as and. Losing Bone Hearts or the Red Hearts contained within will not affect the chance to find a Devil Room or Angel Room, with the exception of The Forgotten who receives a penalty for a Bone Heart breaking. Acquiring an empty Red Heart container while you have a filled Bone Heart will fill the new heart and empty the Bone Heart. Any character with health can pick up bone hearts, but characters who cannot possess Red Heart Containers cannot fill them with Red Hearts.

Bone Hearts can be filled with Rotten Hearts. They can also be used for Devil Deals or Black Markets, unless the character can't have red heart containers.

Rotten Hearts


Rotten Hearts are special Red Hearts unlocked by entering for the first time. Rotten Hearts spawn two friendly Blue Flies for each one that Isaac possesses upon clearing a room. They can be used to fill empty Red Heart containers or replace the rightmost Red Heart if there are no empty containers. It is not possible to have half a Rotten Heart; rather, each Rotten Heart is equivalent to half a heart. Normal hits will fully deplete them and hits which would deal a full heart of damage will deplete two Rotten Hearts or, if Isaac has only one Rotten Heart, a Rotten Heart and half a red heart. Losing Rotten Hearts will not affect the chance to find a Devil Room or Angel Room.

Broken Hearts


Broken Hearts are special Red Heart containers that only appear when using, , or a card. Broken Hearts are considered empty Red Heart containers, but cannot be removed or refilled under normal circumstances. They cannot be used for any Devil Deals, they cannot be refilled with any form of Heart, or replaced by any Heart Container. They are permanently applied to the character for the rest of the run, even after using items that can revive or change the current character. They also do not let you benefit from stat upgrades for having empty red heart containers like. The only way to remove them is to donate to a Confessional Machine, which has a chance to remove them with each donation. Replacing all 12 Heart Container slots with Broken Hearts will cause Isaac to instantly die, and reviving after this causes Isaac to have a fake Heart Container that will disappear upon obtaining any new item or taking any form of damage.

Trivia

 * Upon entering a room with only half a heart left, a small yellow spot, presumably urine, will appear underneath Isaac.
 * If Isaac has, a bloodstain will appear instead of urine.
 * As, a bloodstain will appear instead of urine.
 * Eternal Hearts have a special animation if used by a character who cannot use red hearts, where the animation of the hearts joining together will show their respective heart type.
 * There is an unused half Coin Heart graphic left in the files.