Why Is My Poop Green? 9 Causes and When to Worry

Green poop is most commonly caused by eating high amounts of green foods, but it can be caused by antibiotic use or other intestinal conditions, like irritable bowel syndrome and gut infections.

In newborns, the presence of dark green poop is generally normal, as it is usually meconium. This is the first stool that is formed in the newborn's intestines.

If you notice green poop for more than 2 or 3 days, or if you have green poop with other symptoms like stomach pain, bloating, vomiting or tiredness, it is important to see a doctor to determine the underlying cause and begin the most appropriate treatment. Learn more about what your poop color means about your health.

What causes green poop?

Green poop can be caused by:

1. Eating green food

Consuming naturally green food like spinach, broccoli or lettuce can lead to green poop. Stool that is green from diet can occur in both adults and children.  

How to treat: if you have green poop due to the intake of green food, the best thing to help the stool return to its normal is to avoiding eating the same food, at least for a while. The stool will usually go back to being brown once the green food has been excreted from the body, therefore, it is not a cause for a major concern.

2. Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a condition characterized by the inflammation of the intestinal villi, which typically causes stomach ache, flatulence and bloating, but can also lead to the production of green stools or yellow stools.

How to treat: IBS symptoms can be managed by making some lifestyle changes, primarily diet changes and stress management. You are advised to adhere to an IBS diet as directed by a registered dietitian, and to carry out activities that reduce stress levels, which can stop symptoms from getting worse or progressing. 

3. Intestinal infection

Intestinal infections caused by bacteria like salmonella or parasites like Giardia lambli can often cause green poop. This is because stool moves through the intestines much quicker in the presence of infections, which reduces the time that bile and other digestive enzymes have to breakdown the stool. This quicker movement can lead to green diarrhea.

Learn more about the symptoms of parasitic infections in the intestine. 

How to treat: If you suspect you have an intestinal infection, the doctor will assess you and advise treatment as necessary. Treatment may involve the use of medication to treat the underlying microorganism causing the infection. Plenty of fluids and rest can also speed up recovery.  

Check-out home remedies for intestinal infections that you can prepare to complement your doctor's prescribed treatment.

4. Use of antibiotics

Some medication, especially antibiotics, can significantly reduce the amount of flora present in the gastrointestinal tract, This can also have an effect on bile production. When bile comes in contact with specific flora and digestive enzymes, it becomes brown, which contributes to the brown color of stool.  

When antibiotics are taken, the quantity of flora is affected, which causes the bile to remain green, resulting in green poop. Other medications, like iron supplements, may also interfere with bile and digestion and lead to green coloring.

How to treat: Once your doctor has approved you to stop your medication, you should assess your poop color to see if it remains green. If it does, then you should inform your doctor, who may recommend probiotics.

5. Iron supplements

Using iron supplements can change the color of stool, making it appear darker than usual. This is a sign that the body is absorbing iron correctly. However, when the iron in oral supplements are not completely absorbed by the intestine, it can turn your poop dark green or black as a side effect.

Iron supplements are prescribed to prevent and/or treat iron deficiency anemia. It can also be used in some situations where the body needs higher concentrations of this mineral, which can occur in childhood or during pregnancy.

How to treat: If you notice green stools after taking iron supplements, consult the prescribed to determine whether the treatment remains appropriate, or if another dose or form of supplementation (like IV iron) is required. 

6. Bile

Bile is a substance that aids in the digestion process and helps to process fats. This liquid is stored in the gallbladder and produced by the liver.

When diarrhea is present and intestinal flow is faster than the body can absorb nutrients, it is possible that the bile released does not have time to be processed. This can lead to green poop.

How to treat: You should consult a doctor if you have green diarrhea, as it may be a sign of a a bacterial or viral infection. The doctor will likely advise increased hydration and determine whether antibiotics are necessary to prevent complications

Learn more about what causes green diarrhea and what to do to treat it.

7. Medication side effects

In addition to antibiotics, medications like metformin, commonly used to treat diabetes, can affect bile metabolism and gut motility. This can lead to changes in stool color, including the presence of green poop. Metformin may accelerate intestinal transit time, reducing the breakdown of bile and producing green-colored stools.

How to treat: If you suspect a medication is altering your stool color, speak to your doctor. You should not stop treatment without medical advice, as the benefits of the medication may outweigh this side effect. In some cases, alternative medications or dosage adjustments may be considered.

8. Food dyes and green-colored supplements

Synthetic food dyes found in candies, drinks and processed foods may not be fully digested and can color the stool green. Supplements such as spirulina, wheatgrass or chlorophyll-based products can also cause green-colored stools.

How to treat: If you have recently consumed large quantities of green-colored foods, dyes or supplements, you can monitor for 1 to 2 days to check whether stool color returns to normal. If it persists or is accompanied by symptoms, consult a healthcare provider.

9. Rare conditions like Crohn’s disease or celiac disease

Inflammatory bowel diseases, like Crohn’s disease and celiac disease, can affect nutrient absorption and digestion. These conditions may result in bile not being fully processed, causing green stool, especially during flare-ups or when diarrhea is present.

How to treat: You should follow up with your doctor if you have chronic gastrointestinal symptoms, including persistent green poop, especially if you also have fatigue, weight loss or blood in your stool. These conditions typically require long-term treatment and monitoring.

Causes summary

Check out a side-by-side comparison of each cause of green poop and what it can look like:

Green poop in babies

Meconium is the name given to a baby’s first stool, which is actually formed when the baby is still in the mother’s womb. Meconium is thick, viscous and green looking. This is because the gastrointestinal microbiota of the baby is still not completely developed and does not have the necessary bacteria to act on the bile. This makes the poop darker and gives it its green color.

It is normal for the baby to excrete meconium in the first 24 hours of being born. The color and consistency of the stool will progressively change in the following days due to the development of the gastrointestinal tract and consumption of breastmilk or artifical milk.

What to do: Meconium is normal in all babies, however, if the baby does not excrete any green poop after being born or if there are no changes in color within the first week of life, the baby should be assessed by the doctor.  

Learn more about other colors your poop can have and what these changes can mean. 

When to go to the doctor

You should seek medical attention when, in addition to having green stools, you also present symptoms such as:

• Diarrhea;
• Nausea or vomiting;
• Loss of appetite;
• Blood in the stool;
• Headaches or dizziness.

Stool testing and additional exams may be ordered to determine the cause of the symptoms.