Your friend should certainly schedule an appointment with her primary care physician
right away. Vomiting blood is really not a specific symptom of any particular viral infection. Most viral gastrointestinal infections cause symptoms of nausea, vomiting, diarrhea, and a generalized feeling of un-wellness. When people vomit blood, it can come from a variety of different sources. If someone has a viral gastrointestinal infection, oftentimes the blood comes from a small tear that occurs in the esophagus when someone wretches over and over again. We call this a Mallory-Weiss tear. A Mallory-Weiss tear is quite common and usually requires no major medical intervention. It will usually heal and its own and often does not result in significant blood loss. Sometimes vomiting blood can have nothing to do with infection. One of the most common causes of vomiting blood is a bleeding
ulcer. Stomach ulcers are very common and sometimes when they bleed the can cause nausea which can result in vomiting blood. In patients with liver disease, blood vessels known as esophageal varices can enlarge and break easily. This kind of bleeding can be very significant and very life-threatening. In any case, your friend should certainly schedule an appointment with her primary care physician right away. If the vomiting is continuing and it continues to be bloody, then your friend will need an urgent referral to a gastroenterologist
for an upper endoscopy.