5 Causes of Green Poop With IBS.

Our content is not intended nor recommended as a substitute for medical advice by your doctor. Use for informational purposes only.

Green poop is not common with IBS, but it can occur. The green color of poop can result from green leafy vegetables, food colorings, infections, severe attacks of IBS diarrhea, and others.

The following are the most common causes of IBS green poop:

1 . Green leafy vegetables.

Green leafy vegetables contain a green substance called Chlorophyll. Therefore, eating too many green leafy vegetables can lead to dark or even bright green poop.

The poop color change is directly proportional to the amount you eat.

Causes include:


  • Spinach
  • Kale
  • Cabbage.
  • Beet greens
  • Romaine Lettuce.
  • Blueberries.

2. Food colorings.

Green dyes can also lead to bright green poop when consumed excessively.

They cause symptomless dark green poop with no other digestive issues like green vegetables.


  • Dyes or color additives used in AIcohoIic drinks.
  • Green-colored ice pops.
  • Green-colored sodas and soft drinks.
  • Drink mixes.
  • Natural dyes, as with green grapes, cucumber, etc.

3. Severe attacks of IBS-diarrhea.

Severe attacks of IBS diarrhea are common. The IBS diarrhea attack is light brown or yellowish.

When the attack is severe, your poop may turn green in color.

How does stool turn lime green with severe diarrhea?

Bile (bilirubin) is a greenish substance secreted from your liver into the digestive tract (the small intestine and the colon).

Under normal conditions, bacteria that usually live inside your digestive tract will convert the green bilirubin into a brownish substance called (stercobilin) which gives the stool its standard brown color.

With severe diarrhea, the rapid passage of contents of the gut tract will not allow enough time for the bile to turn brown.

Severe diarrhea often manifests with yellow watery diarrhea. As diarrhea continues, patients with severe diarrhea may pass bright or lime green bile in stool.

4. Infection (gastroenteritis) on top of IBS.

Acute infections of the digestive system lead to diarrhea and speeding up of intestine and colon contents. Infection can trigger IBS-like symptoms with diarrhea which may turn green.

The green color of severe diarrhea is often due to the passage of unchanged greenish bile.

Causes include (reference):

Viral: 50%–70%Bacterial: 15%–20%Parasitic: 10%–15%
Enteric adenovirus types 40 and 41CampylobacterCryptosporidium
AstrovirusE ColiIsospora
Some picornavirusesYersiniaMicrosporidium
 C difficile

Whether viral, bacterial, or protozoal, the presence of dark green poop depends on the severity of diarrhea rather than the type of the organism.

Infection is often acquired by contact with an infected person or an infected surface.

Also, the infection can be due to the contamination of food with the organisms or its toxins (foodborne illness or food poisoning).

The more severe diarrhea, the more likely to have dark green poop.

Symptoms of acute gastroenteritis:

  • Sudden onset abdominal cramps.
  • Nausea and/or vomiting.
  • Sudden onset of diarrhea. The diarrhea is often watery and yellow at first.
  • With frequent attacks of watery diarrhea, The poop eventually becomes dark green due to the passage of unchanged green bile.
  • Dark green poop may be a sign of severity and may lead to dehydration, especially in age extremities (children and older people).
  • Fatigue and body aches.
  • Fever may be present (low-grade in viral gastroenteritis and high-grade in bacterial gastroenteritis.
  • Signs of dehydration may occur in severe cases such as extreme thirst, dry tongue, peeing too little urine, deep yellow urine, dizziness, shortness of breath, fast heartbeat. Confusion and coma occur in severe cases of dehydration, particularly in babies and older adults.

5. SIBO.

Bacterial overgrowth means that the naturally occurring microorganisms inside your small intestine increase in number (overgrown).

This overgrowth may have drawbacks on your digestive system function. The “too many” microorganisms may produce too much waste like gases or toxins. And the unwanted gas and waste may cause symptoms like distension, colics, severe diarrhea that may lead to green stool with IBS.

Small Intestinal Bacterial Overgrowth (SIBO) is linked to IBS. But the research is conflicting:

  • Evidence suggests that eradicating this bacterial overgrowth with antibiotics is associated with improvement in IBS symptoms.
  • However, another study found that SIBO is not consistent in All IBS Patients. In this study, SIBO was found in only 4% of IBS patients (they precisely the same percentage of SIBO found in the healthy persons included in the study).

Small intestinal bacterial overgrowth causes malabsorption symptoms including severe diarrhea which may turn green with IBS.

6. Others.

  • Associated food intolerances such as lactose and fructose intolerance lead to severe diarrhea.
  • The recent removal of the gallbladder (post-cholecystectomy diarrhea).
  • Associated conditions such as hyperthyroidism, malabsorption syndromes, etc.

When to worry about green poop with IBS?

See a doctor if:

  • Green poop is associated with severe diarrhea that is not going away
  • Prolonged bright or lime green poop periods for more than days without apparent cause.
  • Nausea or vomiting.
  • Sings of dehydration include extreme thirst, peeing little urine, dark urine, confusion, or coma.
  • Fever.
  • Presence of blood in the stool.