What Causes Black Stool?

Black stool (melena) should first prompt consideration of dietary causes. For instance, recent consumption of foods such as pork blood, sheep blood, duck blood, or pig liver can cause stool to appear black—this is a normal, benign phenomenon. Secondly, certain medications may be responsible: some individuals take medications for underlying health conditions, and certain drugs themselves are dark-colored. After ingestion, these medications may be excreted in the stool, turning it black. If the black stool resolves after discontinuing the medication, it is likely drug-induced and generally not a cause for concern—a normal, transient effect that typically improves upon cessation of the drug.

Pathologically, black stool is commonly associated with upper gastrointestinal disorders—for example, peptic ulcer disease or acute gastritis. Additionally, certain infectious diseases—including sepsis and typhoid fever—can also lead to melena. If black stool occurs consistently after daily alcohol consumption—and no black-stool-inducing foods or medications have been ingested—it is advisable to seek medical evaluation. Recommended tests include routine stool analysis and fecal occult blood testing; upper gastrointestinal endoscopy (gastroscopy) may also be performed to definitively identify the underlying cause. Patients should adopt a light, bland diet, avoid smoking and alcohol, and refrain from overeating or binge drinking.