Vomiting material that is black or very dark brown is an alarming symptom requiring immediate attention. This dark-colored vomit, often described as having the texture and appearance of coffee grounds, indicates the presence of altered blood in the stomach. Medically termed hematemesis, this sign is associated with bleeding within the upper gastrointestinal (GI) tract and suggests a serious underlying medical condition.
Why Vomit Appears Black or Dark
The distinctive “coffee ground” appearance results from a chemical reaction between blood and stomach acid. When bleeding occurs in the upper GI tract, hemoglobin in the red blood cells mixes with hydrochloric acid. This interaction oxidizes the iron component of the hemoglobin, changing its color from bright red to a dark brown or black shade. The granular appearance comes from the blood partially coagulating as it is digested by gastric juices.
Vomit containing bright red, fresh blood suggests a rapid or active bleed, often closer to the mouth or throat, or a very severe bleed that has not had time to react with acid. Conversely, black or coffee-ground vomit signals a slower or older bleed, allowing sufficient time for the acid to act upon the blood before expulsion. The dark color provides a physiologic clue about the location and duration of the internal bleeding.
Common Causes of Upper Gastrointestinal Bleeding
The most frequent source of black vomit is bleeding from the upper digestive system, including the esophagus, stomach, and the duodenum (the first part of the small intestine). Peptic ulcers are a common cause, as these open sores on the stomach lining or duodenum can erode into a blood vessel. Ulcers often result from damage caused by the Helicobacter pylori bacterium or the prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs).
Another cause is severe inflammation of the stomach lining, known as gastritis. This irritation, often caused by excessive alcohol consumption, certain medications, or chronic acid reflux, leads to erosions that bleed. Esophageal varices represent a particularly severe cause, involving enlarged, fragile veins in the lower esophagus that can rupture suddenly. These varices develop in individuals with advanced liver disease, such as cirrhosis, where obstructed blood flow causes pressure to build up in surrounding vessels.
Forceful and repeated vomiting can cause a Mallory-Weiss tear, a laceration in the esophageal lining near the stomach. Although these tears often heal on their own, the initial bleeding may be significant enough to produce dark vomit. In more serious scenarios, conditions like stomach cancer can cause chronic internal bleeding as tumors ulcerate and break down tissue.
Non-Bleeding Reasons for Dark Vomit
Dark-colored vomit is not always due to internal bleeding, but medical confirmation is necessary to rule out serious causes. The consumption of certain foods or medications can temporarily mimic the appearance of coffee-ground emesis. Specific dark foods, such as black licorice, blueberries, or large amounts of dark chocolate, can result in very dark brown or black vomit shortly after ingestion.
Certain oral medications and supplements also cause this discoloration.
Common Non-Bleeding Causes
- Iron supplements, as the iron oxidizes and turns black when mixed with stomach contents.
- Activated charcoal, often used to treat poisoning.
- Bismuth subsalicylate compounds found in some over-the-counter stomach relief medications, which react with sulfur to create a black substance.
- Swallowed blood from a severe nosebleed or mouth injury, which is partially digested by stomach acid before being vomited.
Recognizing Emergency Symptoms and Next Steps
Black vomit must be treated as a medical emergency due to the potential for significant blood loss. The immediate concern is the risk of hypovolemic shock, a life-threatening condition caused by a sudden, severe loss of blood volume. Emergency symptoms accompanying black vomit include feeling dizzy or faint, a rapid heart rate, pale or clammy skin, shortness of breath, confusion, or continuous vomiting.
A healthcare provider will perform a physical examination and order blood tests to assess blood loss and check for underlying issues like liver dysfunction. Diagnostic procedures often involve an upper endoscopy, where a flexible tube with a camera identifies the source of bleeding. The physician may stop the bleeding during the endoscopy by applying clips, heat, or injecting medication directly into the site.