I bite the side of my tongue sometimes, can this be deadly? and make it swollen? this happens some times when i'm eating, or are nervous. dangerous?

Biting one's tongue: Biting one's tongue both figuratively and in reality is not deadly. It is a common habit and one you can learn to break.

Not really: Nothing is impossible, but in over 40 years of practice I have never heard of any serious problem with a patient accidentally biting their tongue. I have done it on occasion myself. It's sore, sensitive and an annoyance for awhile. If it's a habit, you should try to find other less harmful habits or try any number of relaxation techniques. Speak to your own physician about it.