Black vomit, medically termed hematemesis, is a deeply concerning symptom requiring immediate medical evaluation. Hematemesis means vomiting blood, and the dark color indicates the blood has been exposed to stomach acid. This presentation signals serious bleeding within the upper gastrointestinal tract, which includes the esophagus, stomach, and the first part of the small intestine. Recognizing this symptom and seeking prompt care is important because internal bleeding can rapidly lead to significant blood loss and shock.
Why Vomit Appears Black
The distinctive black color and granular texture, often described as “coffee grounds,” result from a specific chemical reaction. When blood enters the stomach, hydrochloric acid rapidly interacts with the hemoglobin in red blood cells. This interaction causes the iron within the hemoglobin molecule to undergo oxidation.
This chemical change transforms bright red hemoglobin into hematin, a dark brown or black compound. The granular appearance is due to the blood clotting and coagulating in the acidic environment. This dark, oxidized blood signals that the bleeding source is located within the stomach or duodenum, allowing for acid exposure.
Serious Gastrointestinal Conditions
Black vomit indicates upper gastrointestinal bleeding caused by several serious conditions. The most frequent cause is a bleeding peptic ulcer, an open sore developing on the lining of the stomach or small intestine. These ulcers form due to an imbalance between stomach acid and the protective mucosal lining.
The two main culprits are infection with Helicobacter pylori bacterium and the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs). H. pylori damages the mucosal layer, allowing acid to erode deeper tissues. NSAIDs inhibit the COX-1 enzyme, which produces protective prostaglandins that maintain mucosal integrity. Bleeding occurs when the ulcer erodes into a blood vessel wall.
Another serious cause is the rupture of esophageal varices, abnormally enlarged veins in the lower esophagus. These varices develop in people with severe liver disease, such as cirrhosis, where scarring obstructs blood flow through the liver. This blockage creates high pressure in the portal vein system, known as portal hypertension. This forces blood to reroute into smaller, fragile veins that can rupture, causing massive hemorrhage.
Other causes include severe gastritis and esophagitis. Gastritis is inflammation of the stomach lining, while esophagitis is inflammation of the esophagus, often from chronic acid reflux. A Mallory-Weiss tear is a laceration in the mucous membrane of the lower esophagus. These tears are caused by sudden, forceful vomiting or retching that rapidly increases intra-abdominal pressure.
External Factors That Mimic Black Vomit
While most cases involve internal bleeding, some external substances can mimic the appearance of black vomit. These substances turn stomach contents a dark shade, resembling oxidized blood. A common example is the ingestion of medications containing bismuth subsalicylate, such as Pepto-Bismol.
The bismuth component reacts with sulfur in the digestive tract, forming black bismuth sulfide. This reaction can temporarily turn the tongue, stool, and sometimes the vomit a dark black color. Oral iron supplements can also result in black or dark green discoloration. Certain dark-colored foods, such as black licorice, dark chocolate, or grape juice, may also cause temporary dark discoloration. Regardless of a suspected non-bleeding cause, anyone observing black vomit should seek medical advice to rule out a hemorrhage.
When to Seek Emergency Care
Black vomit requires immediate emergency medical attention to identify the source of bleeding and stabilize the patient. The primary concern is hypovolemic shock, a life-threatening condition caused by rapid blood loss. Symptoms accompanying dark vomit that necessitate an immediate 911 call include any sign of shock.
These signs include feeling faint or lightheaded, especially when moving, or experiencing a rapid heart rate. Other emergency symptoms are confusion, pale or clammy skin, or a sudden change in mental status. Upon arrival, the care team focuses on stabilization by monitoring vital signs and initiating intravenous fluid resuscitation. Diagnostic steps involve blood work and sometimes inserting a nasogastric tube to evaluate the bleeding extent. The definitive diagnostic and therapeutic procedure is an upper endoscopy, which uses a flexible tube to visualize the source and stop the bleeding directly with clips or cauterization.