Your poops appear unusually dark one day. Really dark. But you didn’t eat a bag of Oreos or licorice.

But wait – you had cranberry juice yesterday. Should you worry about why your stools are uncharacteristically dark?

If you know your stools’ normal color range, then you’ll surely notice if one day they’re darker than usual.

For many people, this sets off alarm bells, because old blood will darken stools.

If there’s bleeding in the upper GI tract, then this will turn bowel movements dark because by the time the blood gets from that location to the anus, it’s old rather than fresh.

This dark substance, when mixed with stools, can give them an almost black hue.

Darker-than-usual bowel movements can be pretty alarming to anyone over 50, though people under 50 are far from immune to conditions that cause bleeding in the upper GI tract such as an ulcer and Crohn’s disease, and of course, colon cancer, even esophageal cancer.

What about cranberry juice?

“Cranberry juice, owing to its red color and penchant to trigger bowel movement soon after digestion, can potentially turn stool red,” says Nadeem Baig, MD, a board certified gastroenterologist and hepatologist at Monmouth Gastroenterology, a division of Allied Digestive Health.

Dr. Baig adds, “When mixed with normally colored brown stool, the coloring can make it darker.”

Of course, having had cranberry juice doesn’t mean that the dark color can’t have an unrelated cause.

What you should do is check your stools in the ensuing days to see if the darkness persists – without having any more cranberry juice or other foods that can make stools dark or nearly black-appearing such as Oreos, large amounts of chocolate, beets/beet juice and licorice.

If an unexplained dark color recurs, and especially if you have new-onset symptoms such as stomach pain, nausea, constipation and/or fatigue, then it’s time to make an appointment with a gastroenterologist – no matter what your age.

All Known Causes of Very Black Stools

Dr. Baig’s specialties include gastrointestinal cancers and liver disease, plus gallbladder, biliary tract and pancreatic disorders. He is an assistant clinical professor of medicine at the University of Medicine and Dentistry of NJ/Robert Wood Johnson Medical School.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  


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