One of my husband’s old girlfriends got into occultism and Ouija boards while they were dating. Her personality went from normal to withdrawn and morose, to insane. She tried to cave in his skull with an object, and she once launched herself, screaming, onto the hood of his car as he was leaving.
At the time, I was acquainted with the girl through work, and I can attest to her personality change. No one ever knew how she would react from day to day.
Yes, Ouija boards are dangerous. I recommend you read this testimony of a person I know about his experience:
Limit the Effects - When and why I quit using the Ouija Board. (1964-03)
my own personal experience was been a sense of fear & evil when once asked to play with it. Needless to say, I passed on the ‘game’.