answer:I don’t think it is possible (though I have seen people allergic to multiple antibiotics). For example, people allergic to penicillin-like antibiotics are often also allergic to sulfa drugs. That said, new antibiotics are out that don’t resemble the old ones, so she could take those (of course, she could claim the same thing). Something here isn’t right, though. If she has a bacterial infection serious enough to be out of work, and she cannot take antibiotics, she would be really sick, or possibly die (unless it is something “mild”, like a urinary tract infection). Conversely, she might have a viral illness, but that wouldn’t require antibiotics, so the story is fishy.