Black or Tarry Stool: When to Worry

TL;DR:
Black or tarry stool can be caused by harmless factors like certain foods or supplements, but it can also indicate serious internal bleeding or gastrointestinal conditions. Prompt medical evaluation is essential especially if accompanied by other symptoms like pain or dizziness.

Overview

Black or tarry stool is a symptom that can indicate various health issues ranging from benign dietary causes to serious medical emergencies. Understanding the potential causes and recognizing when to worry can help you take timely action. In this post, we explore the common causes, warning signs, and when it’s critical to seek medical help for black or tarry stool.

Key Causes

Gastrointestinal Bleeding

One of the most concerning causes of black or tarry stool is bleeding in the upper gastrointestinal (GI) tract, such as the stomach or esophagus. When blood is exposed to digestive enzymes and stomach acid, it turns black and sticky, leading to what’s called melena.

Peptic Ulcers: Sores in the stomach or duodenum lining can bleed and cause melena.
Gastritis: Inflammation of the stomach lining can result in bleeding.
Esophageal Varices: Swollen veins in the esophagus may rupture, especially in people with liver disease.

Medications and Supplements

Certain medications and supplements can cause stool discoloration without indicating serious problems.

Iron Supplements: These commonly produce black stools as iron oxidizes.
Bismuth Subsalicylate: Found in medicines like Pepto-Bismol, it can darken stool temporarily.
Activated Charcoal: Used for poisoning treatment or detox, it may cause black stool.

Dietary Causes

Some foods naturally cause black or dark stools, which are harmless and temporary.

Black Licorice, Blueberries, or Blackberries: Can darken stool color.
Beets and Spinach: Though typically cause reddish or green stools, combined with digestive factors may appear darker.

Other Medical Conditions

Less common causes of black or tarry stool include:

Malignancies: Tumors in the upper GI tract may bleed intermittently.
Diverticulosis: Though more common cause of bright red blood in stool, sometimes can cause dark stools if mixed with upper GI bleeding.

When to Seek Help

Black or tarry stool always warrants careful attention. You should seek urgent medical evaluation if you experience:

Persistent black stools lasting more than a few days without an obvious dietary cause.
Signs of blood loss or anemia, such as weakness, fatigue, dizziness, or shortness of breath.
Abdominal pain or cramping, which may signal ulcers or serious inflammation.
Vomiting blood or material resembling coffee grounds, indicating active bleeding.
A history of liver disease, alcohol use, or NSAID use, which increase risk of bleeding.

If you notice any of these, visit a healthcare provider immediately. They might recommend endoscopy, blood tests, or imaging to diagnose the cause and initiate treatment.

Try It Yourself

Curious about what your stool color means?
Try our free poo colour decoder! It’s a simple tool to help you understand your digestive health and know when to seek medical advice.

Taking note of changes in stool color like black or tarry stools is an important part of monitoring your digestive health. While many causes are harmless, some require prompt medical care—don’t hesitate to reach out to a healthcare professional if you’re unsure.