What kind of shot would be administered to an elderly patient for vomiting?

Phenergan/Zofran: If not allergic to those.

Vomiting: More than likely zofran (ondansetron).

There are many: Different nausea medications for all age groups. I prefer zofran, as it works quickly and doesn't make you tired. I've seen many fewer negative reactions to zofran vs phenergan, (promethazine) or kytril. It is always hard to tell how someone is going to react to any of those meds until they take it, or if they have had previous testing for their cytochrome p450 systems, and you know how each drug will react.