“When should you go to the ER for vomiting and diarrhea?”

If it is uncontrollable and you are getting dehydrated

If you cannot hold down any fluids (orally) for 24 hrs I'd say go to hospital bc your losing fluids rapidly (diarrhea) and not able to replenish any of them. This will inevitably lead to severe dehydration and potentially kidney injury and electrolyte derangements. Dont wait til you're too weak to call for help. If you're diabetic, Just go! You cannot let your sugar drop and you can't hold food and liquid down that's a life threatening situation. If you need life sustaining meds and cannot keep them down, GO!!!

When you can't keep fluids down and/or feel you are getting dehydrated.