Hematemesis
PillRebirthUnlocked
How do you unlock Hematemesis?
Verified starting unlockSource data confirms that no unlock is required.
Sets Isaac's red heart health to 1, then spawns 1-4 Red Hearts. This fills Isaac's first red heart container (even if Isaac's red health is less than 1) and empties the rest, including Bone Hearts. This effect does not count as damage. If used without any red heart containers, no health will be deducted, but red hearts will still spawn. If used in aSuper Secret Room containing aBlack Heart or Eternal Heart, it will spawn those types of hearts instead.
Available from the start
No unlock needed — this is available in every new save file.
What unlocking Hematemesis leads to
Nothing depends on this yet.
Source: bindingofisaacrebirth.wiki.gg
Imported 2026-09-13