Why Does Blood Induce Fainting in People?

Check out why blood induces fainting in some people. Have you ever wondered why some people faint at the sight of blood? Fear of blood is classified as a phobia, which is an intense irrational fear of something that causes your body to react by going into fight or flight mode. But unlike other phobias, the fear of blood along with injury, and injection phobias can actually cause a person's blood pressure and heart rate to go up and then suddenly drop, which can cause them to lose consciousness.