2. Black Flags
If you notice your stool is very dark or black, and is “coffee ground-like in appearance,” it could be a sign of bleeding in the upper gastrointestinal tract, warns Healthline.com. “The blood is older and therefore travels down the intestinal tract,” it explains.
However, it’s not just blood that can turn your poop black. The source says that iron supplements, bismuth medications (to treat upset stomach and heartburn), and even black licorice can have a similar effect.