The modern idiom “open Pandora’s box” means to start something that releases many unexpected problems.
The expression comes from the Greek myth in which Pandora opens a container and troubles escape into the world. In everyday English, it is used figuratively when an investigation, decision, invention, or conversation creates consequences that are difficult to control or reverse.
The idiom is not limited to one particular kind of problem. It can describe political controversy, technological risk, family conflict, or any chain of complications triggered by one action. The phrase usually carries a warning that the consequences will spread beyond the original intention.
The wording is itself historically layered. Hesiod described a pithos, or jar, while the “box” form became standard after Renaissance translation and later European usage. The idiom therefore preserves a popular version of the myth rather than the exact object in the earliest surviving account.
“Open Pandora’s box” is different from “open a can of worms,” although both expressions describe unleashing complications. The Pandora phrase specifically invokes the mythological source and its association with widespread evils.