lose one's head (over)
To panic.
"Let's not lose our heads," the captain cried. "We have good lifeboats on this vessel."
When Mel saw a dog in the street right in front of his car, he lost his head and drove onto the sidewalk and into a tree.
If the politician hadn’t gotten stirred up and lost his head, he never would have criticized his opponent unfairly.
To become deeply infatuated with someone.
Don't lose your head over Jane; she is already married.