Short answer
Green poop is most often caused by leafy greens, green food dye, iron supplements, or diarrhea that pushes food through before bile turns it brown. If you feel well and it clears in a few days, it is often not a concern. See a doctor if it lasts, or comes with fever, severe pain, blood or signs of dehydration.
Why is my poop green?
Poop is usually green because of green foods or dye, iron supplements, or food moving through the gut too quickly for bile to turn brown.
Bile is a green-yellow fluid your liver makes to digest fat. It turns brown as bacteria in your intestines change it. If food moves through too quickly, bile does not finish changing color, and stool comes out green. Food and supplements can also add green color directly.
- Leafy greens and green foods. Spinach, kale, broccoli, green smoothies, spirulina and chlorophyll supplements.
- Food coloring. Green, blue and purple dyes in frosting, drink mixes, candy and cereal.
- Iron supplements. Iron can turn stool dark green or nearly black.
- Diarrhea. Fast transit leaves bile green. Green watery stool is common with stomach bugs.
- Antibiotics. They can upset gut bacteria and loosen stool, which sometimes turns green.
- Infections and gut conditions. Some gut infections, and conditions that cause frequent loose stools such as irritable bowel syndrome or inflammatory bowel disease, can be linked to green stool.
Is green poop normal in babies?
Green stool is very common in babies. Newborns pass a dark green-black stool called meconium in the first days, and breastfed and formula-fed babies can both have green stool that is usually normal. See the baby poop color chart for what is typical at each age.
When is green poop harmless, and when should you worry?
Green poop is usually harmless if you feel well and it clears within a few days. See a doctor if it lasts more than a week, or comes with fever, severe pain, blood or signs of dehydration.
Usually harmless
- You ate green foods, dye or took iron in the last day or two
- You feel well and the color clears within a few days
- You have mild, short-lived loose stool without other symptoms
Call a doctor within a day or two
- Green stool lasts more than a week with no food or medicine explanation
- Diarrhea lasts more than two days
- You have cramping, fever or unexplained weight loss
Get care now
- Green stool with blood, severe belly pain, or repeated vomiting
- Signs of dehydration: very dry mouth, little or no urine, dizziness
- A baby who is feeding poorly, is unusually sleepy, or has fever
Warning signs to know
These are signs that published medical guidance says need prompt or urgent care. The list is not complete, and ticking boxes cannot tell you whether you are ill. If you are worried, contact a clinician whatever you tick.
Questions people ask
Is green poop a sign of cancer?
Green stool is rarely a sign of cancer. It almost always comes from diet, supplements, dye or fast digestion. Colon cancer is more often linked with blood in the stool, a lasting change in bowel habits, or unexplained weight loss.
Why is my poop green and watery?
Watery stool moves through the gut quickly, so bile does not have time to turn brown. Stomach infections and food poisoning are common causes. It usually clears within a few days. See a doctor if it lasts more than two days or you become dehydrated.
Can green poop be caused by stress?
Stress can speed up digestion, and quicker transit can lead to looser, greener stool. It is a possible contributor, not a diagnosis.
Can antibiotics cause green stool?
Yes. Antibiotics change your gut bacteria and can cause loose stool that looks green. If you have severe or bloody diarrhea during or after antibiotics, contact your doctor.
How long does green poop last?
If it comes from food or dye, it usually passes within one to three days. If it lasts longer than a week with no cause you can point to, have it checked.
Sources
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