The phrase "with a grain of salt" means to take something with skepticism or doubt. This idiom has several synonyms which can be used interchangeably such as "with a pinch of salt", "with a grain of skepticism", "with some reservations", "with caution" and "with a skeptical eye". These synonyms can be used in situations where one needs to be cautious about the authenticity of something they have received or heard. It is essential to take these situations with critical thinking and doubts to avoid being misled. Using these alternative phrases can add spice to one's language and make them sound more eloquent and precise.