Is it safe to exorcise someone who is possessed?

My boyfriend truly believes that he is possessed but he thinks that if he gets an exorcism, he will die. Is this true in all cases or only in some? Also, he believes that when the demon first entered his body, the demon forced him to shoot himself in his head, leaving behind a major dent instead of a fatal wound. Is it possible for the demon to injure the host in such a way, without destroying them? Please, if anyone has any remedies or procedures that I can use to help ease his pain and possibly end his suffering, please send me some useful feedback. Thank you.