What is the common English idiom for an action that creates many unforeseen problems, inspired by Pandora’s myth?

The common English idiom is “opening Pandora’s box,” meaning to begin an action that creates many unforeseen problems. It comes from the myth in which Pandora opens a sealed vessel and releases evils into the human world.

The expression is used in journalism, politics, business, science, and everyday conversation. It usually warns that investigating or changing one issue may produce a much wider set of consequences. The phrase does not necessarily mean that every result will be harmful, but it strongly suggests that the consequences will be difficult to control.

The idiom’s wording reflects later translation history. Hesiod’s original vessel was generally a large jar, not a small box. Even so, “Pandora’s box” became the established English form and is now more widely recognized than the ancient description. Hope’s presence in the myth adds further complexity, because the story is not simply about evils escaping.