Poop Decoder
Why is my poop black?
Often iron or medicine. Sometimes blood. Iron pills, bismuth stomach medicine, activated charcoal, black licorice and blueberries all turn stool black. Black, sticky, tar-like stool with a foul smell is different: it can mean bleeding higher up the gut.
See a doctor right away if
- Black, tarry stool, especially with a foul smell
- Red blood in your stool, or maroon-colored stool
- You vomit blood, or feel dizzy or lightheaded
- Pale or clay-colored stool for several days, or with yellow skin or dark urine
- Bloody stools with weight loss, dizziness or fever
Call 911 for an emergency. When to see a doctor
Harmless or not?
The harmless kind
MedlinePlus lists black licorice, blueberries, blood sausage, iron pills, activated charcoal and medicines containing bismuth as causes of black stool. If you've had one of these, it's the likely reason.
The kind that needs a doctor
Black or tarry stool with a foul smell can be a sign of bleeding in the esophagus, stomach or first part of the small intestine. Blood turns dark as it's digested on the way down. Peptic (stomach) ulcers are the most common cause of that kind of bleeding.
Can't tell? Get it checked
A doctor can test stool for blood. Tell them about iron, bismuth or charcoal you've taken, because they can change the color without any bleeding.
Sources: MedlinePlus, Black or tarry stools; MedlinePlus, Taking iron supplements.