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Conditions

GI bleeding and iron-deficiency anemia

Bleeding can happen anywhere in the digestive tract, from the esophagus to the rectum. Sometimes it's obvious; sometimes it's hidden and shows up only as iron-deficiency anemia on a blood test. Either way, the source should be found.

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Call 911 or go to the ER for:
  • Vomiting blood or material that looks like coffee grounds
  • Large amounts of red blood or clots from the rectum
  • Black, tarry stools with dizziness, fainting, a racing heart or shortness of breath

Signs to see a gastroenterologist soon

  • Small amounts of blood on the toilet paper or in the stool
  • Black stools without other symptoms (iron and bismuth can also darken stool)
  • Iron-deficiency anemia, especially in men and in women after menopause
  • Fatigue, pale skin or shortness of breath with low iron

Common causes

Upper GI: ulcers, inflammation of the esophagus or stomach, and abnormal blood vessels. Lower GI: hemorrhoids, fissures, diverticular bleeding, polyps, colitis and colon cancer.

How the source is found

Many causes can be treated during the scope itself.

Common questions

Can low iron cause blood in the stool?

No. Low iron doesn't cause bleeding. It's usually the other way around: slow, often unseen bleeding in the digestive tract is one of the most common causes of iron-deficiency anemia, especially in men and in women after menopause. Iron pills can turn stool dark green or black, which can look like blood. Red blood, or black and tarry stool, should still be checked.

Can I have GI bleeding without seeing blood?

Yes. Small amounts of bleeding can be invisible and show up only as low iron or a positive stool test. That's why unexplained iron-deficiency anemia is a common reason for an upper endoscopy and colonoscopy.

Is it just hemorrhoids?

Often, but bleeding shouldn't be assumed to be hemorrhoids without an evaluation, especially after age 45.

Can I just take iron?

Iron treats the anemia, not the cause. Finding the source comes first.

Questions about bleeding or anemia? Call (813) 400-0543 or send a message.

For heavy bleeding, call 911.

Dr. Brian Frank, MD
Written and reviewed by Brian Frank, MD
Board-certified gastroenterologist (ABIM). Last reviewed October 28, 2026.

This page is general information, not medical advice. For a medical emergency, call 911.