confused man

Having green poop, or stool, can occur due to dietary changes, such as switching to a high-kale diet or eating more of other high-chlorophyll plants. Having green poop can also occur as a result of:

  • an underlying medical condition
  • antibiotics
  • a recent medical procedure
  • a bacterial infection

Why Is It Usually Brown, Anyway?

The characteristic brown color of your excrement is a leftover mix of dead red blood cells and waste from the bacteria in your bowels. The bile in your intestines is usually a yellowish green color, but the bacteria add the rest of the hue. Besides making your poop brown, the bacteria perform vitally important functions, like helping you to absorb the nutrients from your meals. 

Most likely, your feces are another color because your food isn’t spending enough time in your digestive tract. For example, if you have diarrhea, the contents of your intestines may be rushing through the process too quickly to allow bacteria to give your poo its characteristic hue.

It’s Probably Something You Ate

The most common reason for green stool is a dietary habit or change, such as being on a high-kale diet. Dark green vegetables contain a lot of chlorophyll, the chemical that allows plants to make energy from the sun. This can turn your Cleveland Brown into a Green Bay Packer. That doesn’t mean there’s something wrong. Keep eating those greens, kids. 

Some foods contain food coloring that doesn’t get processed properly. This can also leave a colorful residue in your stool. So if you wake up after a St. Patrick’s Day spent imbibing green beer and notice something off when you go to the bathroom, you probably just need some water.

But It Might Be Something Else

But sometimes, green poop isn’t just your colon’s idea of a practical joke. Besides diarrhea, there are underlying medical conditions that can drastically alter your bowel movements.

Those conditions will come with other symptoms besides green poop, so a little tint to your poo won’t be the first thing you notice is awry.


If you’ve recently been prescribed a course of antibiotics, especially a strong one for a major infection, the medication can clear out large parts of your gut’s bacteria. This lowers the population of the brown-staining lower intestinal bacteria. Probiotics, such as yogurt or kombucha, can help restore balance to your intestinal flora.

Medical Procedures

Stool discoloration can also occur after a major medical procedure, like a bone marrow transplant. Should your body reject the transplant, a condition known as graft versus host disease may develop and cause serious gastrointestinal upset, which can lead to diarrhea and green stool.


Parasitic and bacterial invaders can also be causing your green stool. Yes, your gut lining is made up of billions of bacteria that serve a vital purpose to the body. Outsiders, however, can wreak all sorts of havoc on your intestinal output. 

Bacteria like Salmonella (the common culprit behind most food poisoning), the water parasite Giardia, and norovirus can cause your guts to flush quicker than normal, which can lead to green stool. 

If you’re reading this while vacationing, you may be experiencing traveler’s diarrhea. Fortunately, this isn’t considered a serious disorder and usually resolves itself quickly without treatment.

The Takeaway

If you experience green stool as a one-off, it’s highly unlikely to be cause for concern.

However, seeing other colors in your stool may indicate an issue. Bright red signifies potential bleeding in the lower intestine. A black or dark tarry brown could indicate bleeding in your upper intestine. But remember, it could also be that beet salad from lunch.

In most cases, green stool is nothing to worry about. Long-lasting bouts of discolored stool may signal something more serious, but a one-time occurrence usually just means you’re eating your vegetables.