I know that the Torah prohibits the consumption of blood. Does this apply to my own blood as well?
When the Torah tells us that we are allowed to eat the meat of kosher animals, we are warned that "…you shall not eat the blood…."
Although human blood is not included in this Biblical prohibition, it is nevertheless forbidden. This is because human blood resembles animal blood; one who observes people eating human blood might believe it is permitted to consume animal blood.
If you cut yourself while preparing food and a drop of blood accidentally falls into your dish, just get rid of the spot where the blood landed. If the blood got lost in the food and is unnoticeable, Halachah does not require you to throw out the dish, since there is no concern that an observer would think the food contains animal blood.
On the same note, if you are eating an apple and notice that there a flecks of blood in the apple (presumably from a cut on your gum) you cannot eat that part of the apple. However, if you are bleeding in your mouth, and the blood did not leave your mouth, you have nothing to worry about.
This is all from a halachic perspective. From a health perspective, you might wish to be more wary of consuming human blood.
Oh, and please be careful when cutting salads—even if it will still be kosher.
Rabbi Eliezer Posner