how do you get hematemesis (the vomitting of blood)? is it contagious through contact?

Answer 1

doubtful that it is contagious, although it depends on the underlying problem. most common causes are ulcers (which can be caused by aspirin or other similar products and alcohol abuse) sometimes a cause can't be found...but when you say contact, i have to wonder what kind of contact? not with the blood itself? please be careful.

Answer 2

It COULD be from something as simple as a ruptured blood vessel. Or, something along the lines of a bleeding ulcer. How much blood are we talking about and what color? You should get this checked out.