###Human: 3-year-old son has diarrhea for a week. Is this something serious? ###Assistant: Hello. If there is no blood in stools, it is mostly viral. It usually gets settle in five days. Important here is maintaining hydration. Make sure you give him plenty of fluid, ORS (oral rehydration solution). If he is vomiting, you can ask your doctor to prescribe Ondansetron. Give him probiotics and keep a watch on urine output. If he is passing adequate urine, then there is no point of worry.