Green Poop: 10 Possible Causes and What It Means

For the average person, passing green poop could be quite an alarming event.

You’ll probably wonder if this strange colored poop is linked to some dangerous health problem.

Well, in this article, we would be discussing green stools in details. You will learn what determines stool color, possible causes and what to do next.

Determinants Of Stool Color

During digestion, the liver secretes bile (a light green substance). Bile helps in the digestion of fat. When you eat a meal containing some fat, the gallbladder releases bile to break down the fatty acids.

As the process of digestion continues, bacteria and enzymes in the large intestine act on bile and change its color from green to yellow to brown.


This is why the normal poop color is brown.

10 Possible Causes Of Green Poop

Here’s a list of some causes:

1. Consumption of Some Green Foods

Most times, it means that you are eating green colored foods like vegetables. It is usually nothing to worry about, and your poop should return to normal once you change your diet. Isn’t it really amazing how what we eat can affect our stool color?
This is the most common reason why people pass green poop. It may simply result from consuming meals including vegetables like:

  • Spinach
  • Kale
  • Broccoli
  • Swiss Chardboy
  • Boy Chok
  • Beet greens
  • Arugula
  • Watercress.

The reason why these foods may cause this change is that they contain chlorophyll, the pigment that gives plants their green color. These foods are more likely to cause a change in poop color when taken in large quantities like in juices and smoothies.

2. Food Dyes

Some foods that contain food coloring may lead to the passing of green colored poop. This is popular during holidays like St. Patrick’s days and Christmas.

In 2015, the term ‘GreenPoop’ became a popular hashtag when many Americans who tried Burger King’s “Halloween Whooper” passed green stools. Many people even shared photos of their toilet experiences on social media.

The “Whooper” got its color from a food dye that was baked into its bun.

3. Diarrhea

Diarrhea is when you pass more than three stools in a day.

When food rushes through the digestive system too quickly, like in diarrhea, there isn’t enough time for enzymes and bacteria to act on bile- the green pigment that turns brown during digestion. This leads to greenish diarrhea. Sometimes diarrhea can be associated with the presence of mucus in stools.

4. Antibiotics

The use of antibiotics can kill the normal ‘good bacteria’ found in the intestines. These bacteria help the digestive system and are partly responsible for the brown color of poop.


Along with digestive enzymes, these bacteria act on bile, changing its color. But when they are destroyed, poop color could be green.

5. Medication

Some drugs can cause this condition as a side effect.

Examples of some of these medications are:

  • Iron supplements
  • Laxatives (can cause diarrhea)
  • Indomethacin
  • Medroxyprogesterone (a contraceptive)

6. Alcohol and Coffee

Consumption of large quantities of coffee and alcohol can cause a laxative effect, making food rush through the intestines and decreasing the time it takes for the bile to be digested.

7. Meconium

This happens in newborn babies. Meconium is actually the first poop that a baby passes. It is normally dark-green, sticky and surprisingly does not smell!

Another uniqueness of meconium is that it is sterile, it contains no bacteria. It is primarily made up of materials the baby ingested when in the womb like dead skin cells, hair, mucus, amniotic fluid, and water.

So, if in the first days of a baby’s life, you notice dark-green stools, don’t be very worried, it is most likely meconium. It clears off after a few days and the stool color should change to brown or yellow.

8. Pregnancy

It is not uncommon for pregnant women to have this symptom. Most of the times, it is nothing to worry about. Some of the vitamins and supplements that constitute the routine antenatal medications, can cause green poop.

Also, in the third trimester, towards the end of pregnancy, food may pass through the intestines at a faster-than-normal rate, causing this condition.

9. Intestinal Diseases

This is related to diarrhea. Medical conditions that affect the normal function of the intestines can cause green diarrhea.

Some conditions may be related to micro-organisms and parasites, while others may be inflammatory changes or intolerance to substances like lactose and gluten. When infections cause it, they can also lead to the presence of blood in stool.

Here are some intestinal conditions that can lead to this condition:

  • Parasitic infections (like Giardia)
  • Bacterial infections (like Salmonella)
  • Viral infections (like norovirus)
  • Irritable bowel syndrome
  • Celiac disease
  • Lactose intolerance
  • Crohn’s disease
  • Ulcerative colitis
  • Premenstrual syndrome (PMS)
  • Laxative abuse
  • Hyperthyroidism

10. Medical Procedures

Some medical procedures can lead to a change in poop color.

For example, major procedures like bone marrow transplants. If the recipient’s body rejects the transplant, it can trigger a condition known as graft versus host disease.

This condition has an acute phase that is characterized by abdominal discomfort, cramping, nausea, vomiting, and diarrhea- leading to green stools.

Also, abdominal surgeries like cesarean sections can sometimes also cause it.

What to Do Next

As we had earlier established, most cases are caused by diet.  Green foods and dyes are largely responsible for turning the color of poop from brown to green.

Therefore, most times, it is not something to worry about. If it is caused by diet, the stool color should return to normal within a few days.

It is often not an emergency unlike black or red stools. Black poop (also medically known as melena) and red stools usually signify bleeding in the digestive system and should be checked.

However, if you keep passing it for several days, have persistent diarrhea, or have other symptoms like abdominal pain, nausea or vomiting, you should consult your doctor.

Diarrhea, if severe, can be life-threatening.

The fluid loss from the frequent, loose stools can lead to dehydration. Green stools are sometimes caused by diarrhea, so, if you are passing continuous loose stools, you should to see a doctor and get yourself treated.


Green poop is not usually a medical emergency and is mostly caused by foods taken in. However, it can be a sign of other ongoing conditions that may be dangerous.

It is important to look out for other symptoms and remember that checking out your poop from time to time can be very helpful.

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Omiete Charles-Davies, MBBS

Dr. Omiete Charles-Davies graduated from the University of Lagos with a degree in medicine and surgery. He is a licensed medical doctor and has worked in different private and government-owned hospitals as a general medical practitioner. For fun, he loves to travel and experience new cultures.