In modern English, what does “open Pandora’s box” mean?

In modern English, “open Pandora’s box” means to create or unleash many unforeseen problems.

The idiom comes from the Greek story in which opening a sealed vessel releases harmful forces into the human world. English speakers use it figuratively when an action begins a chain of complications that is difficult to control or reverse. The expression usually suggests that the consequences were not fully anticipated.

The phrase is often used in journalism, politics, law, science, and everyday conversation. It does not normally refer to a literal container, and it can describe both an individual decision and a broader policy or discovery. The wording “Pandora’s box” became standard even though ancient Greek versions describe a pithos, or jar.

The idiom should not be confused with “skeletons in the closet,” which refers to concealed embarrassing facts. Both expressions involve troubling revelations, but Pandora’s box emphasizes consequences unleashed by an action.