What does it mean if a cat is throwing up blood? Or if he is coughing up blood?

Hi, brionybeeching!

It means that you should be taking the cat to the vet as soon as possible! Is there anything keeping you from doing that?

It could be something really serious, and the more time before taking the cat to the vet may make things worse! We can't really diagnose this sort of thing here. Only someone trained, who can examine the animal in person, can do that.

Thanks!

Could be gastro-intestinal bleeding, mouth ulcers from toxins, both of which can come with kidney issues, or even a sign of liver disease. Or perhaps he's had an injury. If it's gastro-intestinal bleeding a stool sample, if you can get it, may help.

But in any case, you do need to get him to a vet.