Is there any disease or anything that can cause you to death or untill death or that wont go away from oral?

Fairly safe: Hiv can probably be transmitted by the oral route; the ape models are more impressive than the data from humans but acquiring this is a catastrophe and a reason not to do this unprotected. If by chance you are not immune to hepatitis b, you can catch it this way & it may hang on for keeps. Syphilis and gonorrhea are famously transmitted by oral sex; curable but no fun at all. Know your partner.