Well, I keep a whole storehouse of anti-Lestrange curse mixtures down my hollow leg, don't you know.

Actually, I can't claim anything other than blind instinct. First off, I wasn't even sure she hit me at first. Then when I did feel it, and started sicking up, I did the thing that felt most natural, which was change to Padfoot. I headed for water, as well - that was more or less instinct, only Bill here found a source that confirmed salt-water would neutralise many curses of that type. So I waded in shoulder-height, rinsed out my mouth with saltwater, and just kept right on doing that until it felt more or less safe.

Changed once too early. Had help from then on, looking after me in dog form and keeping me well salted.

Otherwise, yeah. She'd have done for me.