Vomiting and diarrhea are usually caused by a virus. Viral illnesses usually run their course without treatment by a doctor. 
However, seek emergency care if vomiting or diarrhea is severe or persistent, says the <a href="[BASEDOMAIN]/healthinfo/bouncelink.aspx?shortcut=acep" target="_blank">American College of Emergency Physicians</a>. For children, severe vomiting means they vomit everything, vomit nearly everything or vomit eight or more times per day, according to the <a href="[BASEDOMAIN]/healthinfo/bouncelink.aspx?shortcut=aap" target="_blank">American Academy of Pediatrics</a>. In these cases, there can be a risk of dehydration. Head to the ER if there's blood (that's not from a nosebleed) in the vomit.
Reviewed 8/29/2023

Do you need a doctor? Vomiting and diarrhea

Most cases will go away on their own, but some need a doctor's attention.