Is it good to workout when you have stomach flu?

Difficult: It is not necessarily bad or good, but would be difficult. When you are fighting off the stomach flu, you will often need rest and have time to replenish your fluids to avoid dehydration, so engaging in a strenuous work-out is not the best idea, nor would you probably be able to do it. Better to rest and relax while you get better, then restart your work out routine when feeling well. Best wishes.