Ondansetron popularly called Zofran. You can get it for migraines, especially mild migraines, if nausea is one of the main symptoms (or you just say that it is)

You really don't want to use it if your body actually needs to expel some heinous toxic shit, which is why doctors don't like to just hand it out without knowing what's wrong with you. But it's great for that post-purge nausea and reactive vomiting so that you can successfully hydrate.