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What does green stool in adults mean?

Green stool in adults can be alarming, but it usually indicates some underlying cause that may or may not require medical attention. Let’s explore the potential reasons for green stool in adults and when you should see a doctor.

What Causes Green Stool in Adults?

There are several possible causes of green stool in adults:


Green foods or supplements containing chlorophyll like spinach, kale, wheatgrass, and spirulina can cause green stool. Green food coloring, found in frosting, drink mixes, ice pops, and more can also turn stool green. Typically diet-related green stool is temporary and subsides once the foods are eliminated.


Certain antibiotics like ciprofloxacin or tetracycline, iron supplements, and laxatives containing cascara or senna can cause green stool. It usually resolves after stopping the medication.

Celiac Disease

People with celiac disease have an immune reaction to gluten that damages the small intestine’s lining and prevents proper absorption of food. This leads to pale, loose, greasy stools. In some cases, the stool may appear green.

Crohn’s Disease

Crohn’s disease causes inflammation anywhere along the digestive tract. One potential symptom is green diarrhea due to the rapid transit time of stool through the intestines. Stool may also contain blood in some cases.

Food Poisoning

Certain types of food poisoning caused by bacteria like Salmonella, E. coli, and Clostridium difficile can result in watery, green diarrhea as the body attempts to rid itself of the infection.

Bile Conditions

Problems with bile production or the flow of bile into the small intestine from the liver or gallbladder allows more green-colored bile to mix into the stool, resulting in green diarrhea. Common causes include:

  • Gallstones blocking a bile duct
  • Inflammation of the gallbladder (cholecystitis)
  • Scarring of bile ducts from surgery, disease, or injury (biliary stricture)

Rapid Transit

Sometimes green stool occurs when food moves too quickly through the intestines. Stool can appear green because bile doesn’t have time to break down completely. Causes of rapid transit include:

  • Viral, bacterial, or parasitic infection
  • Food poisoning
  • Inflammation from conditions like inflammatory bowel disease
  • Adverse reaction to medication
  • Overactive thyroid (hyperthyroidism)
  • Tumor obstructing the bowel
  • Nervous system or muscle conditions affecting digestive tract contractions

Anal Fissures

Tears or cracks (fissures) in the lining of the anus often cause some bleeding during bowel movements. This small amount of blood may stain the stool green.

When to See a Doctor

In most cases, temporary or intermittent green stool is not a cause for concern. However, schedule an appointment with your doctor if you notice any of the following:

  • Prolonged green stool lasting more than 3 days
  • Intense or bright green stool color
  • Bloody, black, or pale gray stool
  • Diarrhea lasting more than 3 days
  • Severe pain or cramping
  • Unexplained weight loss
  • Fever higher than 101°F (38°C)

Seeking timely medical care is recommended if you have green stool combined with severe symptoms as it could indicate a serious underlying problem requiring treatment.

Main Causes of Green Stool in Adults

Cause Description Additional Symptoms
Diet Green foods or food coloring None or mild diarrhea
Medications Iron supplements, antibiotics, laxatives None or mild diarrhea
Celiac Disease Immune reaction to gluten Diarrhea, bloating, weight loss
Crohn’s Disease Inflammation of digestive tract Abdominal pain, bloody diarrhea, weight loss
Food poisoning Bacterial, viral, or parasitic infection Nausea, vomiting, cramps, diarrhea
Bile conditions Blocked bile duct, gallbladder issues Pain in abdomen or right side, yellow skin or eyes
Rapid transit Quick food passage through intestines Diarrhea, cramps, infection, inflammation
Anal fissures Tears or cracks in anus Painful bowel movements, rectal bleeding

Diagnosing the Cause of Green Stool

To determine the underlying cause of green stool, doctors may recommend the following diagnostic tests:

Physical exam

Checking for tenderness, distension, or masses in the abdomen that could indicate obstruction or inflammation.

Blood tests

Help identify or rule out conditions such as viral or bacterial infection, celiac disease, gallbladder problems, and thyroid disorders.

Stool sample testing

Checking for blood, bacteria, parasites, or other pathogens that could be causing diarrhea or food poisoning.

Imaging tests

Such as abdominal X-rays, CT scans, or MRI scans to look for blockages, strictures, gallstones, tumors, or problems with intestinal anatomy.


Inserting a camera into the colon and large intestine to check for inflammation, ulcers, polyps, cancer, or other abnormalities.


Snaking a thin tube with a camera down the throat helps the doctor evaluate the esophagus, stomach, and upper part of the small intestine.

Treatments for Green Stool

Treatment depends on the underlying cause of green stool. Options may include:

  • Diet changes – Removing any green foods or dyes and sticking to a bland diet until stool normalizes.
  • Medication changes – Switching medications or lowering dosages if side effects are causing green stool.
  • Supplements – Probiotics and digestive enzymes to help restore intestinal balance.
  • Surgery – To correct obstructions, drain abscesses, remove polyps or tumors, or repair anal fissures.
  • Medications – Antibiotics for infections, anti-inflammatories like sulfasalazine for IBD, bile acids for absorption issues.
  • IV fluids – For dehydration from severe vomiting or diarrhea.

Prevention Tips

You can reduce the likelihood of green stool by:

  • Drinking plenty of fluids to stay hydrated.
  • Avoiding unnecessary antibiotics or laxative use.
  • Practicing good hygiene when handling food.
  • Cooking meats thoroughly and washing produce to prevent infection.
  • Managing medical conditions like Crohn’s disease or gallstones.
  • Eating more fiber to promote regularity.

When to Seek Emergency Care

Seek immediate medical attention if green stool occurs with:

  • Severe rectal pain
  • Inability to pass stool or gas
  • High fever with profuse sweating
  • Confusion, dizziness, or fainting
  • Blood pressure drops
  • Dehydration showing as increased thirst, dry lips and mouth, little or no urination
  • Black, tarry stool indicating bleeding in the upper GI tract

Rapid evaluation and treatment is crucial if green stool is accompanied by these red flag symptoms, as they can precede life-threatening complications including sepsis, bowel perforation, intestinal obstruction, significant blood loss, shock, or organ failure.


Green stool in adults has a wide range of potential causes. In many cases it is temporary and not a major concern, especially if it occurs in isolation without other symptoms. However, if persistent green stool is present along with worrisome symptoms like diarrhea, pain, bleeding or dehydration, prompt medical evaluation is warranted. Diagnostic tests along with appropriate treatment can deal with any underlying issues leading to green stool.