How to Determine the Cause of Black Stool

To determine the cause of black stool, it is important to consider factors such as diet, medication use, accompanying symptoms, medical history, and bowel habits, along with an overall clinical assessment. If black stools persist, appear tarry, or are accompanied by discomfort, prompt medical evaluation is recommended.

1. Evaluate dietary factors: Consuming animal blood products like pork or duck blood, or dark-colored foods such as black sesame seeds, black beans, mulberries, or blueberries, may temporarily darken stool color. This type of black stool is typically not sticky or foul-smelling, resolves within 1–3 days after stopping intake, and does not involve other physical discomfort.

2. Consider medication effects: Taking iron supplements for anemia or bismuth-containing medications (e.g., gastric mucosal protectants) commonly causes non-pathological black stools. Stool color usually returns to normal gradually after discontinuation, without associated symptoms such as abdominal pain, dizziness, or fatigue, so there is generally no need for excessive concern.

3. Observe accompanying symptoms: Tarry, sticky, shiny, and foul-smelling black stools, especially when accompanied by abdominal pain, bloating, acid reflux, or heartburn, may indicate upper gastrointestinal bleeding due to conditions such as gastric ulcers or gastritis. If associated with dizziness, palpitations, weakness, or cold sweats, significant blood loss may be occurring and requires urgent medical attention.

4. Review medical history: Individuals with a history of gastric or duodenal ulcers may experience black stools due to ulcer-related bleeding. Those with liver cirrhosis or esophageal-gastric varices should be alert to possible rupture and hemorrhage. Patients with a history of acute gastric mucosal lesions or gastric cancer may develop black stools due to disease progression and mucosal damage.

5. Assess bowel patterns: An isolated episode of black stool without other symptoms is often due to dietary or medication-related physiological changes. However, repeated episodes, changes in bowel habits, or associated weight loss and decreased appetite warrant timely investigation for underlying organic diseases.

Maintain regular eating habits, avoid spicy, hard, or irritating foods to protect the gastrointestinal mucosa, establish consistent bowel routines, monitor changes in stool color and consistency, avoid indiscriminate drug use, and adopt healthy lifestyle practices to reduce gastrointestinal injury.