Well, when a human has had vampire blood, they get stronger and faster than normal. When off it those powers start to diminish, then they get even weaker, start to shake, lose their appetite, get a fever, it's almost like they get a flu. But, if it gets past that part, they'd experience that they are easily wounded, even scratching an itch can cause them to bleed or a particularly hard touch can cause a bruise, they could also experience terrible dehydration and organ failure.