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What Causes Green Poop?

A piece of green stool
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Written by Jack Wilkinson, MD.
Fellow, Cornell/Columbia New York Presbyterian Child Psychiatry Program
Last updated April 18, 2024

Green poop quiz

Take a quiz to find out what's causing your green poop.

Green poop can be caused by eating certain green foods, an infection that causes diarrhea, bile, or a side effect of medication. In addition, irritable bowel syndrome can cause green poop and stomach pain. The treatment depends on the cause.

6 most common cause(s)

Green poop quiz

Take a quiz to find out what's causing your green poop.

Take green poop quiz

Common green poop symptoms

Your poop (or "stool") is probably consistent in color if you take the time to notice. While the shade can vary from light to dark, most people's stool is brown, and doctors agree that brown is the most common color. Green poop, however, isn't always healthy, but it's certainly not a reason to panic. Stool color is determined by a variety of factors, such as diet, medications, and some gastrointestinal disorders. In most cases, green is the least abnormal color, and some even consider it to be on the spectrum of normal stool. Red, black, and white stool also warrant a visit to your physician.

Common accompanying symptoms

It's likely to also experience:

Why is your poop green?

More about stool coloration

The brown color of stool comes from bilirubin, a product produced by the liver when it routinely breaks down old blood cells. Bilirubin then enters the intestines, where it mixes with digested food, enzymes, and gut bacteria. If stool travels through the intestines at a healthy speed, bacteria interact with the stool content and turn it brown. Any changes to this process, such as during illness, can mean that stool is processed differently and will turn out to be a different color.

Diet and medication-related causes

The following are likely causes of green stool due to things you ingest.

  • Dietary changes: The most common cause of green stool is eating green food, such as leafy greens like spinach or kale. Food coloring found in certain foods such as gelatin or ice pops can also be to blame.
  • Antibiotics: While you may take them for an infection elsewhere in the body, antibiotics also have a strong effect on the healthy bacteria in the gut that process stool.
  • Other medications: Certain pain-relievers and over-the-counter supplements may change the color of stool depending on how you digest them.

Natural causes

Causes of green stool due to more natural bodily processes include the following.

  • Bile: This substance, produced in the liver and stored in the gallbladder, helps digest fats and is naturally green in color. It is usually broken down in the intestines, but sometimes it remains in stool.
  • Young age: Newborns may have green stool in the first few days of life before it changes to a yellow or brown color.

Illness-related causes

Causes of green stool due to illness may include the following.

  • Gastrointestinal diseases: Conditions like Crohn's Disease or Irritable Bowel Syndrome impair absorption in the intestines and change the makeup of stool.
  • Parasites: Though uncommon in the developed world, parasites can cause green stool and are possible if you have traveled outside of the country or have eaten raw food.
  • Gastroenteritis: An infection that causes diarrhea forces stool to move through the intestines much more quickly than usual, so bacteria in the gut do not have time to digest normally.

Possible early irritable bowel syndrome (ibs)

Irritable bowel syndrome (IBS) is very common problem that affects the large intestine. It can cause stomach pain, cramps, bloating, constipation, or diarrhea. Doctors think that IBS is caused by the brain sending wrong messages to the bowels, such as during times of high stress, causing physical changes. The formal criteria for this diagnosis requires 3 months of symptoms. Therefore you may have an early presentation.

Rarity: Common

Top Symptoms: fatigue, abdominal pain (stomach ache), nausea or vomiting, stool changes, constipation

Urgency: Primary care doctor

Viral gastroenteritis (stomach bug)

Viral gastroenteritis (stomach bug) involves inflammation of the stomach and intestines. This illness can be caused by many different viruses, including Norovirus, Rotavirus, Enteric Adenovirus, Sapovirus, and Astrovirus. Infection with one of these viruses leads to a combination of nausea, vomiting, diarrhea, fever, and stomach cramps. Not everyone will have the same symptoms or intensity of symptoms. When diarrhea and/or vomiting is severe, dehydration can occur.

Without any alarming symptoms (such as persistent vomiting, severe abdominal pain, or severe dehydration), gastroenteritis is typically safe to treat at home. This condition is contagious and can be spread through close contact with other people.

Viral (norovirus) infection

Norovirus infection is caused by the highly contagious Norwalk virus. It spreads when any trace of stool or vomit from an infected person contaminates food or drink, or gets onto any surface. Anyone who consumes the food or drink, or touches the surface and then their mouth, will become infected.

Norovirus brings on severe gastrointestinal upset which is very unpleasant but rarely dangerous. Symptoms include diarrhea, vomiting, stomach pain, fever, and body aches for one to three days. The greatest risk is dehydration due to the severity of the symptoms.

Because norovirus is, indeed, a virus, antibiotics will not help. The best treatment is good supportive care, which means providing plenty of fluids along with mild pain relievers until the patient recovers. Do not give aspirin to children.

If the dehydration does not improve quickly, medical help should be sought. Doctors can provide IV fluids through recovery.

The best prevention is frequent and thorough handwashing, as well as washing all fruits and vegetables. All foods must be properly cooked, especially shellfish.

Normal variation of constipation

Constipation means bowel movements which have become infrequent and/or hardened and difficult to pass.

There is wide variation in what is thought "normal" when it comes to frequency of bowel movements. Anywhere from three times a day to three times a week is considered normal.

As long as stools are easy to pass, laxatives should not be used in an effort to force the body to a more frequent schedule.

Constipation is usually caused by lack of fiber in the diet; not drinking enough water; insufficient exercise; and often suppressing the urge to have a bowel movement.

A number of medications and remedies, especially narcotic pain relievers, can cause constipation.

Women are often affected, due to pregnancy and other hormonal changes. Young children who demand low-fiber or "junk food" diets are also susceptible.

Constipation is a condition, not a disease, and most of the time is easily corrected. If simple adjustments in diet, exercise, and bowel habits don't help, a doctor can be consulted to rule out a more serious cause.

Rarity: Common

Top Symptoms: abdominal pain (stomach ache), nausea, stomach bloating, constipation, constipation

Symptoms that always occur with normal variation of constipation: constipation

Symptoms that never occur with normal variation of constipation: vomiting

Urgency: Self-treatment

Normal occurrence of diarrhea

Diarrhea can be an indication of serious illness – especially in young children – but in some cases it has a much simpler cause and can be easily cured.

If there are simply frequent loose stools – three or more times per day – without other symptoms of illness, the most common cause is food or drink.

Overuse of caffeine, beer, or wine has a laxative effect on some individuals. The artificial sweeteners sorbitol and mannitol are known laxatives, as are some herbal supplements and some over-the-counter vitamin and mineral preparations.

Lactose intolerance, or the inability to digest the natural sugar in milk, causes digestive upset and diarrhea.

Diarrhea can cause dehydration and mineral imbalance no matter what the cause, so it is still important to manage it.

The best treatment is to remove some items or supplements from the diet and watch the results. This will show which items are causing the diarrhea.

It's always wise to use any new supplements in moderation so that if the trouble recurs, the cause will be plain.

Rarity: Common

Top Symptoms: diarrhea, mild diarrhea

Symptoms that always occur with normal occurrence of diarrhea: diarrhea

Symptoms that never occur with normal occurrence of diarrhea: bloody diarrhea, severe diarrhea, worsening diarrhea, being severely ill, ill appearance

Urgency: Self-treatment

Non specific stool change

There are many factors affecting the appearance of someone's stools. Often a variation in stool color and/or consistency is caused by food or medicines. Leafy greens and certain vegetables like spinach and kale can make stool look green. Iron supplements and medicines containing bismuth like Pepto-bismol can turn stools black. It looks like your stool change is probably a variation of normal.

You can wait and watch for now. If your symptoms do not resolve on their own within a few days or you get any new symptoms, check in again here or contact your healthcare provider.

Rarity: Common

Top Symptoms: black stool, green poop, dark brown stool, red stool

Symptoms that never occur with non specific stool change: tarry stool, weight loss, rectal bleeding, fever

Urgency: Wait and watch

Irritable bowel syndrome (IBS)

Irritable bowel syndrome is commonly known as IBS. Normally, the muscles of the colon, or large intestine, contract and relax to push food along. It's thought that in IBS, the muscles randomly contract either too strongly or too weakly and therefore cause alternating bouts of diarrhea or constipation.

The exact cause is not known. Food allergy/intolerance; stress; hormonal imbalance; and infection or bacterial overgrowth in the colon may play a role, as well as an overly sensitive gastrointestinal nervous system.

Pre-menopausal women who suffer from depression or lead very stressful lives may be most susceptible.

Symptoms vary among individuals, and often come and go. These include abdominal pain and cramping; bloating; gas; diarrhea; and constipation. IBS is not associated with serious illness such as cancer, but symptoms may interfere with quality of life.

Diagnosis is made through patient history, physical examination, and ruling out any other cause. Imaging may also be done.

Treatment begins with improved diet and stress management. Antibiotics, antidepressants, and other medications may be attempted.

Intestinal infection by giardia parasite

Giardiasis is a common intestinal infection caused by the microscopic protozoan parasite Giardia lambia. It is found in contaminated water, even from city supplies and swimming pools. Giardia can also be spread through contaminated food or through direct contact with an infected person, even if they show no symptoms.

Young children and their caretakers are most susceptible, since children wear diapers or are toilet training. Anyone without access to clean drinking water is also at risk.

Symptoms include abdominal cramps with gas and bloating, and copious watery diarrhea.

Treatment is important. Dehydration and malnutrition can occur from the diarrhea, especially in young children. Lactose intolerance, or the inability to digest milk, can remain even after the infection clears.

Diagnosis is made through examining stool samples under a microscope.

Treatment is a course of antibiotics, either in liquid or pill form.

Frequent and thorough handwashing is the best prevention, as is using only bottled, purified water at all times for drinking and cooking.

How to treat green stool

In the majority of cases, green stool may indicate a slight change in the digestive system but is not a major concern.

At-home treatments

The following measures may be enough to get you through a bout of green stool.

  • Keep track of what you're eating: Since dietary changes are the most common cause of green stool, keep a food diary and compare meals to stool output. In most cases, you'll experience green stool in a day or so after you've indulged in that kale salad or green smoothie.
  • Review your medications: Prescription labels will often indicate if changes in your stool may occur after taking a certain medication. Over-the-counter medications and natural supplements are among the most commonly overlooked offenders.
  • Be patient if you're ill: Most infectious causes of stomach upset and diarrhea resolve on their own with hydration and rest. While your stool may turn green while you're ill, it will likely return to its healthy color after the illness has run its course.

Here are some over-the-counter treatment options and when you might need to see a doctor.

Probiotics: These can help restore the natural balance of your gut bacteria, which can be upset by antibiotics or infections that might cause green stool. A product like Culturelle or Align could be beneficial.

Digestive Enzymes: If your green poop is due to indigestion or consuming foods that are hard to digest (like leafy greens), digestive enzymes can help. Products like Beano or Digest Gold can assist in breaking down those tough fibers.

Hydration Electrolytes: Especially if your green poop is accompanied by diarrhea, it's crucial to stay hydrated. Consider OTC rehydration solutions like Pedialyte to maintain electrolyte balance.

When to see a doctor

If you experience the following, see a physician promptly.

When it is an emergency

Seek help right away if you have:

  • A very large volume of stool: Especially if it is dark black or bloody
  • Signs of severe dehydration: Such as fast heartbeat, dizziness, or passing out

FAQs about green poop

Can green poop be caused by stress?

Generally, no, green poop is not due to stress. It is most often due to eating leafy green vegetables, green food coloring, or green foods. However, it can also be due to increased gut motility (speed). Food moving faster through the gut allows less time to break down bile, a green substance that the body naturally produces to digest fats. If bile is not digested, poop may appear dark greenish.

Can green poop be a sign of infection?

No. It is uncommon to produce green poop as a sign of infection. However, if an infection causes your bowels to move more quickly, you may produce green poop as a result. As stated in the prior question, fast-moving food may not give bile a chance to digest, causing green (bile-colored) poop.

Why is my poop green when I'm pregnant?

Green poop is generally not used to diagnose any illness. It can occur because of so many other causes, many of which are normal, that physicians do not use it often as a sign of a particular diagnosis. Green poop while pregnant may be due to iron pills if you have been given them, or if you are eating more leafy greens.

Does teething cause green poop?

No, teething does not cause green poop. Changes in an infant's diet that occur concurrently with teething, however, may produce green poop. Some parents will introduce their child to green baby foods or more partially solid food when they begin teething, and this may change the color of their feces.

Why does my green poop smell like sulfur?

Green poop can take on a sulfur smell. Sulfur-smelling or foul-smelling stools can be a sign of a gastrointestinal infection, most notably, giardia. Most gastrointestinal infections resolve within a week to 10 days. If your symptoms persist, or you begin to feel weak or are unable to keep fluids in without vomiting, you should see a physician.

Questions your doctor may ask about green poop

  • Have you experienced any nausea?
  • Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
  • Any fever today or during the last week?
  • Have you had any changes in your weight?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

Hear what 2 others are saying
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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Green StoolsPosted February 10, 2024 by P.
Since I’ve been taking anti gas meds, my stools are green.
Stomach bugPosted January 12, 2022 by S.
My 9 yr old ate some pizza for dinner that night he spewed than he was fine no temp next day he was fine eating normal 2 days later he ate hamburgers for dinner than he spewed up again than he was fine 4 days later he started developing chest constant under his left arm spreading across to his breast muscle and middle of chest I took him to the doc he said he has a stonach bug and pulled muscle as the week has gone on he's developed constant slight abdominal pain moving from under the rib cage and lower abdominal pain aswell as back pain its been 12 days on and off with pain around the 7th day he had diarehha and Green poo lasting 1 to 2 days and I've been giving him bland and light meals but dairy and heavy foods have hurt his stomach hiw long does the stomach hurt is it just a bug getting out or ibs
Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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