How long does it take a giant blood blister to go away?

Hematoma?: A blood blister is caused by a pinch to the skin and is rarely large. A more traumatic event will cause a hematoma, a large collection of blood. Unlike rules about blisters if this is extremely large or doesn't start to decrease in size it may not shrink on its own breakdown of blood products may cause a bigger deeper wound. This needs to be drained by a physician with good wound care thereafter.

Healing time varies: Healing time may depend on the location, size, and the type of treatment.