There are various synonyms for the phrase "run off the rails" that can be used to describe a situation where something goes out of control or loses its intended direction. Some of the common alternatives include going awry, veering off course, derailing, becoming derailed, getting sidetracked, going off track or off the beaten path, losing one's bearings, going off the deep end, coming off the rails, and losing control. These terms can be used in different contexts to depict a situation where things do not go as planned or when someone loses their concentration or focus. Using synonyms can help to add variety and clarity to our language use while conveying the same message.