What is melena?

Melena is when your stool looks dark and sticky, almost like it’s been in a paint bucket with black paint.

Imagine you have a cookie jar full of chocolate chip cookies. If you eat one cookie, your stomach starts working on it, and eventually, that cookie comes out as part of your poop, but instead of being a soft, gooey cookie, it looks more like a crumbly, dark chunk. That’s kind of what happens with melena, except instead of cookies, it's blood from somewhere in the digestive system, and the blood has been digested a little bit.

When blood is in your stomach or intestines, your body breaks it down. The stomach acid mixes with it, and the enzymes from your gut help change the color of the blood, turning it into something that looks dark and sticky, like black paint.

So when you go to the bathroom, instead of seeing bright red blood, you might see a dark, tarry stool, which is melena. It’s like the body took some blood and turned it into a kind of “black cookie” that comes out with your poop.