There are several synonyms for the phrase "add fuel to the fire," which means to worsen a problem or situation. One such phrase is "pour gasoline on the flames," which has a more intense connotation and implies intentionally worsening a situation. Another similar phrase is "fan the flames," which suggests that someone is exacerbating an already volatile situation. "Stoke the fire" is another synonym that specifically refers to adding fuel to a fire, but can also be used metaphorically to describe the act of making a situation worse. Overall, these synonyms convey the same message as "add fuel to the fire" and can be used interchangeably depending on the context.