The total number of hearts the player has. Two Health means two heart containers, and so on. Note: The only exceptions for this rule is from Azazel and ???, who have -1 health, because Azazel has black hearts, and ??? Has soul hearts.
In Rebirth, the player can have up to 12 hearts in total, this also counts Soul Hearts. In original Binding of Isaac, the player can have up to 12 Heart Containers and there's no limit for Soul Hearts, though they can't be seen if there's more than 12 hearts in the "Life" section.
If Isaac's health surpasses 12 hearts, he will not gain any additional Heart Containers and further Heart Containers granted by most items will be Soul Hearts instead, but Guppy's Paw will be able to use those excessive health stat values to gain further soul hearts. Deals with the Devil can also utilize an excessive health stat.
Should Isaac's health go below 12 heart containers again, the excessive health will be changed into empty heart containers, until the full amount of health (12 containers) is reached again.
Each Heart Container holds one full heart of HP, taking damage will empty one half or one full heart container.
The maximum number of heart containers can be increased by consuming an HP up item or pill, up to a maximum of 12. Any heart containers found past that point can be spent at Devil Room, but not filled with hearts or half-hearts.
Note that in hard mode (only for the Eternal Edition), you can have up to 16 heart containers. Any Heart Container obtained after you hit the 16 limit will grant you a Soul Heart instead.
Empty heart containers can be filled using hearts or half-hearts.
Heart containers can be spent like currency in the Devil Room and can be emptied for cash at a Blood Donation Machine.
??? cannot have any heart containers and all items that gives Heart Containers will give him the same amount of Soul Hearts instead.
Health Up Items
A number of treasures in game will increase your number of heart containers. Numbers in parentheses indicate how much health it heals. Items with an asterisk are only available in Wrath of the Lamb.
If an Eternal Heart is held until the next floor, it will grant you a Heart Container. Collecting 2 of them on the same floor also grants you a Heart Container.
Number in braces denotes the amount of health healed on pickup.
+1 heart container
- Breakfast (1)
- Lunch (1)
- Dinner (1)
- Dessert (1)
- Rotten Meat (1)
- <3 (all)
- Blood Bag (5) (Also increases Speed by 0.3)
- The Halo (1) (Also increases Speed by 0.3, Tears by 0.2, Health by 1, Damage by 0.3, and Range by 2.75)
- Magic Mushroom (1) (Also increases Range by 7.75, Speed by 0.3, Damage by 0.3, and multiplies damage by 1.5)
- Odd Mushroom (Large) (0) (Also increases Damage by 0.3, Range by 2.75 and reduces Speed by 0.1)
- Super Bandage (1) (Also adds 2 Soul Hearts)
- Stem Cells* (1.5) (Also increases Shot Speed by 16%)
- Stigmata* (0) (Also increases Damage by 0.3)
- MEAT!* (1) (Also increases Damage by 0.3)
- Holy Grail* (1) (Also gives flying)
- SMB Super Fan!* (1) (Also increases Tears by 0.2, Damage by 0.3, decreases Speed by 0.2)
- Health Up Pill (0)
- Strength Tarot Card (Temporary) (1)
- Eternal heart* (1) (delayed, see below)
- Possible effect from Liberty Cap* (Temporary) (0) (can copy Odd Mushroom for one room)
+2 heart containers