The matter of drinking a liquid is simple; what you really want to know is whether your body can handle it. After all, you could drink a gallon of lemon-scented bleach, but your body would respond horribly to it.
This sounds really disgusting, but I'm curious: Can humans drink animal blood, or any other kind of blood?
Drinking blood isn't as traumatic to the body as drinking bleach, however. Believe it or not, some tribes in Africa still regularly drink animal blood (sometimes mixed with cow's milk). A story in late January 2008 reported that three fishermen lost at sea survived for 11 days by drinking the blood and eating the meat of a shark they had caught. This makes sense when you consider that there is a lot of water in blood, as well as protein, iron, and other nutrients.
A person who isn't used to drinking blood in any substantial quantity may become nauseated at first, but after some time to adapt, he or she can continue to drink blood without the side effects.
And lest you think that blood appears only in the diets of unmodernized tribes and people in great peril, a quick Internet search is all it takes to find a recipe for Black Pudding, which is essentially a type of sausage whose main ingredient is — you guessed it — animal blood. Although Black Pudding doesn't fall on the list of mainstream culinary dishes, it is still enjoyed by many throughout the world.
But before you go out looking for an ice-cold bottle of Orange-Flavored Hemoglobin (now with Ginseng!), remember this: raw blood can carry all sorts of other viruses, germs, and bacteria that can make you sick. It's best just to avoid drinking it.