Yes, IVs are excellent at preventing nausea or alleviating symptoms. However, in some cases, you may need immediate medical attention instead of taking IV fluids for vomiting. See your doctor or visit an emergency room if you experience: Blood or a dark substance that looks like coffee grounds in your vomit. Nonstop vomiting for four hours straight or bouts of vomiting that don’t stop after 48 hours. An inability to keep any fluids in your body without vomiting. Intense headaches. Uncontrollable diarrhea.