The idiom "give one a taste of his own medicine" essentially means to treat someone the same way they have treated you, with the aim of teaching them a lesson. There are several other synonyms that convey the same message, such as "turn the tables", "get even", "payback", "give someone a dose of their own medicine", or "give someone a taste of their own poison". These phrases can be used interchangeably with the main idiom to convey a similar message of revenge or retaliation. However, it's essential to use these phrases appropriately and judiciously to achieve a productive and peaceful outcome.