Stool Color Changes - Intestinal Bleeding

What part of your GI tract was bleeding, and what was the cause?

Share your story with others:

MedicineNet appreciates your comment. Your comment may be displayed on the site and will always be published anonymously.Patient Comments FAQs

Enter your Comment

Tell us a bit about your background to make your comments more useful to other MedicineNet users. (Optional)

Screen Name: *

Gender of Patient: Male Female

Age Range of Patient:

I am a: Patient Caregiver


* Screen Name will appear next to the published comment. Please do not include your full name or email address.

By submitting your comment, and other materials (collectively referred to as a "Submission") to MedicineNet, you grant MedicineNet permission to use, copy, transmit, publish, display, edit and modify your Submission in connection with its Web site. MedicineNet will not pay you for your Submission. You represent that you have all rights necessary for MedicineNet to use your Submission as set forth above.

Please keep these guidelines in mind when writing your comment:

  • Please make sure you address the question asked.
  • Due to the overwhelming number of comments received, not all comments will be published.
  • When selecting comments to publish, our staff will choose those that are educational and complement the topic. Please try to stay on topic.
  • Your comment may be edited. We would typically edit comments to make them clearer and more readable. We will remove personal information such as last names, email and web addresses, and other potentially harmful information.
  • We will not notify you if your comment has been published. We suggest that you check back on the topic article regularly.
  • We do not provide medical or healthcare advice, treatment, or diagnosis.

Thank you for participating!


I have read and agree to abide by the MedicineNet Terms and Conditions and the MedicineNet Privacy Policy (required).

To prevent our systems from spam, please complete the following prior to submitting your comment.

Please select the white circle:

How does intestinal bleeding change stool color?

One important internal process that can change the color of stool is bleeding into the intestines. The stool may turn black because of chemical changes to the hemoglobin in blood caused, in part, by the action of intestinal enzymes, particularly if bleeding is more rapid and there is a large amount of hemoglobin within the intestines. A color change to black also is more likely if the bleeding occurs in the upper intestine since there is more time for the chemical changes to the hemoglobin to take place as the blood travels through the intestines.

Stool that is black due to bleeding is also "sticky" (tarry) and smells bad. These latter characteristics help distinguish black stools due to internal bleeding from black stools due to the ingestion of iron or bismuth-containing medicines, for example, bismuth subsalicylate (Pepto Bismol).

On the other hand, bleeding that occurs lower in the intestines, particularly in the colon, is likely to cause red or maroon-colored stools since there is little time for chemical changes to the hemoglobin to take place.

Return to Stool Color & Texture Changes (Black, Red, Maroon, Green, Yellow, Gray, Tarry, Sticky)

Stay Informed!

Get the latest health and medical information delivered direct to your inbox FREE!