Have a swelled head

Origin

The phrase conjures a vivid, slightly comical image: a head literally expanding, puffing up with an exaggerated sense of self-importance. While its exact etymology isn't tied to a dramatic historical event, the phrase likely emerged from the common experience of physical swelling due to illness or injury. Just as a physical ailment can distort a body part, an inflated ego distorts one's perception of reality. By the late 19th and early 20th centuries, this vivid metaphor had firmly taken root, particularly in American English, becoming a universally understood way to describe someone whose pride has become unmanageable. It paints a picture of a mind so full of itself that it physically can't contain it.