DayZ tracks three separate things and new players mix them up constantly: health (whether you die), blood (how much you have lost) and shock (whether you black out). You can be at full health and still get knocked unconscious by shock.
The three stats
- Health — hit zero and you die. It drops from injuries, starvation, dehydration and sickness, and regenerates only when you are Healthy (well fed and hydrated).
- Blood — lost by bleeding. Low blood makes your screen desaturate to grey and eventually knocks you out. It refills slowly when you are well fed, or fast with a transfusion.
- Shock — invisible. Big hits (gunshots, falls, melee) fill shock; when it maxes out you go unconscious. It recovers on its own if you survive.
Transfusions and saline
A blood bag transfusion restores a lot of blood instantly, but using the wrong blood type causes a dangerous hemolytic reaction — test with a blood test kit first, or use your own stored blood. A saline bag restores blood with no blood-type risk (just slower), which is why it is the safer field option.
When a teammate is unconscious from blood loss, a transfusion or saline can bring them back; keep pressure off them (stop the bleeding) first.
