Blood clotting. Factor viii is a clotting factor. This is one of many that help you stop bleeding from a cut. If you are low on factor 8, then you will bleed longer than someone who has normal factor 8. The associated condition is called hemophilia a. Treatment is done by replacing the factor 8 when necessary, such as after a trauma or surgery. In severe cases, you may be given factor 8 regularly for prevention.