Interesting question. None, actually. We are lucky that we are very rarely sick, and when the kids catch something, it is usually only an overnight affair and they are much better in the morning. We keep sage and elderberries on hand to make tea for feverish illness (they kill bacteria and viruses), linden blossoms for flu, onions and marjoram to make an infusion for respiratory trouble, and St. John's wort and Rosemary oils to drop in their ears when needed. I burn fir essential oil in our aroma lamp to help take out flying "bugs" and to improve the stuffy air.
What foods help you when you are sick?