Symptoms of internal bleeding in the stomach include vomiting bright red blood and vomitus that looks like coffee grounds, according to WebMD, as is passing black, tarry stools, otherwise known as melena, as stated on Medicine Net. The blood turns black because of chemical changes that take place as it makes its way through the gastro-intensitinal tract, according to Healthgrades, which states that blood may not be visible at all.
Symptoms of internal bleeding in general, including bleeding in the stomach, include weakness, feeling light-headed, shortness of breath, decreased blood pressure and shock, as stated on WebMD. Common causes of stomach bleeding are ulcers, a foreign body, inflammation called gastritis, injury, the bacteria H. pylori, viral infections and cancer. Excessive internal bleeding can be a life-threatening condition.
According to Healthgrades, immediate medical attention is necessary if symptoms such as pale skin, difficulty breathing, serious abdominal pain or loss of consciousness occur. On the other hand, passing black stools can be caused by consuming lead, or such benign factors as taking iron pills and bismuth medicines such as Pepto Bismol, and from eating certain foods such as black licorice and blueberries. A lab test of a stool sample may be necessary to rule out bleeding in the stomach.