Hematemesis is a medical term for vomiting blood. Symptoms of hematemesis may include: - abdominal pain or discomfort; - nausea or retching; - weakness, fatigue, and dizziness; - rapid heartbeat. Causes of hematemesis can be various, including: - peptic ulcers; - esophageal varices; - swallowing blood after a nosebleed; - gastritis; - Mallory-Weiss tears. Immediate medical attention is necessary to determine the cause and initiate treatment, as hematemesis may indicate a serious underlying condition.