Most food poisoning runs its course in 1–3 days, and the main job is staying hydrated. Come in when you can't keep fluids down (we provide Zofran and anti-nausea care), see blood in stool, have a fever over 102°F, or symptoms last beyond 3 days. We test stool when the picture suggests bacteria that need targeted treatment — Salmonella, Shigella, Campylobacter, or C. diff.