The English phrase “Pandora’s box” is recorded from 1579, according to the Oxford English Dictionary.
The expression developed from the classical myth but does not preserve the ancient object exactly. Hesiod’s Greek account describes a jar, commonly translated from the Greek word pithos. Renaissance readers and writers increasingly encountered the story through Latin and later European retellings, and the container became a “box” in English usage.
The phrase eventually became an idiom for an action or subject that releases many unforeseen problems. Its modern meaning usually emphasizes consequences that are difficult or impossible to reverse. That figurative sense is broader than the details of Hesiod’s narrative, which includes divine punishment, the escape of evils, and Hope remaining behind.
The date 1579 refers to recorded English usage, not the date when the Greek myth was created. Ancient versions are many centuries older, while the familiar English idiom belongs to the history of Renaissance and early modern language.