calledkisa:

Blood loss in fiction is often written very unrealistically. So here’s a short guide about blood loss and the effects to help you out a little. 

_{First of all: The average healthy adult human body contains around 5 litres of blood. A healthy person can lose 10%-15% of their total blood volume without experiencing any difficulties and blood donations usually take 8%-10% of the donor’s blood.}

_{Now let's get to the facts about blood loss:}

_{Class I Hemorrhage | 0%-15% | Minimal blood loss
No change in vitals, you may experience anxiousness. In almost all cases blood transfusion won’t be necessary. You will LIVE
Class II Hemorrhage | 15%-30% | Mild blood loss
Rapid heart beat and decrease in pulse pressure. Rapid breathing. Skin may start to lose temperature and start to look pale. You may feel anxious, irritable and confused. In most cases blood transfusion won’t be necessary. You will LIVE
Class II Hemorrhage | 30%-40% | Moderate blood loss
Heart rate increases. Shock. Mental status worsens. Blood pressure drops. Lightheadedness/dizziness. Nausea. Blood transfusion is necessary. If you get help in time, you will LIVE
Class IV Hemorrhage | >40% | Severe blood loss
Symptoms intensify. Probably unconscious. Aggressive resuscitation is required to prevent death. Losing >40% of your total blood volume may be fatal, you will probably DIE.}

_{The chances of surviving after losing 3 litres of blood are REALLY low, the average person doesn’t survive this, so please don’t write a scene where a character loses that much blood without dying. It’s not really realistic.}