You should definately double or even triple dose depending on the severity of the illness. Under normal circumstances our bodies do this automatically when ill or injured. WE have to do it ourselves for our children. When vomiting, they NEED extra meds to help them fight off the illness. Don’t be afraid to give a triple dose or even the shot if really ill (repeated vomiting, high fever, lethargic, shaking, pale or grey skin etc. These are signs of an adrenal crisis. Adrenal crisis is very serious and should be treated as an emergency. Yes, fluids are necessary too. The electrolytes can be out of balance. We always keep frozen pedialyte pops and let our daughter have as many as she wants when ill. Take care and read and research as much as you can and you will better understand this condition. Julia