There are various synonyms for the phrase "allergic to somebody". Some of these include being "unresponsive", "resistant", "disinterested", "indifferent", or simply "not fond" of someone. It can also be described as having a lack of connection, chemistry, or affinity with the person in question. These synonyms suggest a distancing or separation between two individuals, whether it be emotional or physical. It's important to recognize that everyone has different preferences and tendencies when it comes to forming relationships, and being "allergic" to someone simply means that the chemistry or connection is not present.