What is the English idiom “open Pandora’s box” commonly used to describe?

The English idiom “open Pandora’s box” commonly describes unleashing unforeseen problems.

The expression comes from the myth in which Pandora opens a sealed container and troubles spread into the world. In modern English, the phrase is usually applied to an action that creates many difficult, unexpected, or hard-to-control consequences. It often appears in discussions of technology, politics, law, and personal decisions.

The idiom is metaphorical rather than a literal claim about Greek religion. A person can “open Pandora’s box” by starting an investigation, revealing a secret, or introducing a powerful new system whose effects were not fully anticipated.

The expression also preserves the popular “box” version of the story, even though Hesiod described a pithos, or large jar. This is why the idiom’s wording and the oldest surviving Greek account do not match exactly.