What Causes Green Diarrhea and What to Do About It

Passing one solid, green stool is usually nothing to be concerned about. Even green diarrhea may be well within the range of normal stool. Usually, foods like leafy vegetables, supplements, and medications are the cause of this.

However, you can also have green diarrhea from a medical condition such as a stomach infection or digestive disorder that requires immediate or ongoing treatment.

This article describes the different causes of green diarrhea, what to do about it, and when you should talk to your healthcare provider.

Why Green Diarrhea Happens

causes of green diarrhea
Verywell / Joshua Seong

In a broad sense, green stools are caused by two things:

  • It may be directly caused by something you consumed that added color to your stool.
  • It may be indirectly caused by a problem in the digestive process involving a green substance called bile that helps break down fat in the small intestine.

Foods, drinks, medications, and medical conditions are all possible culprits. In some cases, a combination of factors may be involved.

Foods Causes Medication Causes Medical Causes
Dark green, leafy vegetables (like kale) Antibiotics Food poisoning
Purple or blue foods, (like grapes) Anti-diarrheals Food intolerance or sensitivity
Foods made with green, purple, or blue dyes (like popsicles) Depo-Provera Inflammatory bowel disease (IBD)
Coffee Iron supplements Inflammatory bowel syndrome (IBS)
Spicy foods Laxatives Nonalcoholic fatty liver disease (NAFLD)
Alcohol Cholecystectomy (gallbladder removal)

For instance, certain foods can add a greenish hue to a stool. At the same time, the food can have a laxative effect that speeds up digestion.

Under normal circumstances, bile turns a dark brown as it passes through the digestive tract. But, when digestion speeds up, bile can remain green and the stool will usually be loosely formed or watery.

There are also medical conditions that cause stools to move too quickly through the intestines (referred to as "rapid transit" or "decreased colonic transit time"). In cases like this, the stool will more likely be watery.

Foods Causes

If you experience green diarrhea or solid stools that are green, think about what you've eaten over the past several days. Even if the food wasn't actually green, it could still be the cause.

Colored Foods

Foods that can cause green stool include:

  • Large amounts of green leafy vegetables (due to a green pigment called chlorophyll)
  • Purple or blue foods (such as blueberries, grapes, grape or berry juice, and red wine)
  • Green, purple, or blue dyes (such as in candy, popsicles, soda, gelatin, and slushies)

A green stool might not appear for a day or two after eating foods that turn poop green. By then, it is easy to forget what you've eaten. If you think food caused your green stool, just give it a little time. The color should go back to normal in a day or two.

One of the biggest times to see green stools is during holidays when green food dye is commonly used, such as Christmas, Easter, and St. Patrick's Day.

Foods With a Laxative Effect

Some foods have a laxative effect that speeds up digestion and transit times. They can contribute to green stools, especially if you eat a lot. Green diarrhea from laxative foods is often dark green.

Foods with a laxative effect that can cause green diarrhea include:

  • Coffee
  • Spicy foods (such as jalapeños and chili peppers)
  • Alcohol

Medication Causes

Different medications and supplements can give you green diarrhea for a variety of reasons. These include:

  • Iron supplements often make stool dark green that may look black when in solid stools.
  • Laxatives make digestion faster, which leads to green diarrhea due to green bile and higher water content.
  • Antibiotics alter gut bacteria, which can lead to more bile in stools and diarrhea.
  • Anti-diarrheal medications: Pepto-Bismol/Kaopectate (bismuth subsalicylate) can turn stools green or black due to its interaction with digestive enzymes.
  • Depo-Provera contraceptive: This shot may cause green stools, diarrhea, and many other digestive side effects because of its potential effects on the adrenal glands, which produce hormones that help regulate several body functions.

What to Do

If your stools change color or consistency soon after starting a new medication or supplement, check with your healthcare provider or pharmacist to see whether it's a normal side effect.

Medical Causes

The several medical conditions that can cause green diarrhea. Some episodes are acute (meaning that they develop suddenly and tend to resolve quickly) while others are chronic (meaning persistent or recurrent).

Food Poisoning

Green stool may be a sign of food poisoning. Bacteria like Salmonella (the most common cause of food poisoning), the parasite Giardia, and norovirus can cause your intestines to flush quicker than normal, leading to greenish, watery stool.

Other signs of food poisoning include:

  • Nausea and vomiting
  • Abdominal cramping
  • Bloating
  • Rectal pain
  • Chills
  • Dizziness
  • Fatigue
  • Sweating

Food Intolerance or Sensitivity

Food intolerance or sensitivity is when your body has an abnormal reaction to food, causing it to rid itself of the food as quickly as possible. Green, watery stool is a possible symptom along with bloating, nausea, and abdominal cramping.

Some of the causes are autoimmune, meaning that the immune system will mistakenly attack the lining of the intestines by releasing an antibody known as immunoglobulin E (IgE). Others are immune-mediated, meaning that the immune system will overreact to a substance without the involvement of IgE.

Examples of food sensitivities or intolerance include:

Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is an umbrella term for ulcerative colitis and Crohn's disease. Both are serious inflammatory conditions that damage your digestive system. The cause of IBD is unknown but it is thought to be the result of genetics, a weakened immune system, and environmental triggers such as a virus or bacteria.

Diarrhea is a common symptom of both ulcerative colitis and Crohn's disease. The color of diarrhea may on occasion be brown, red (due to intestinal bleeding), or green.

Other symptoms of IBD include:

  • Abdominal pain
  • Bloating
  • Rectal bleeding
  • Unintended weight loss
  • Fatigue
  • Weakness

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a poorly understood condition that causes a wide range of digestive problems. IBS is thought to be caused by a number of factors, including intestinal oversensitivity (resulting in abnormal contractions), poorly coordinated nerve signals between the brain and gut, and a prior intestinal infection with a virus or bacteria.

IBS doesn't always cause diarrhea. Some cases are characterized by constipation and are referred to as constipation-predominant IBS (IBS-C). Others are characterized by diarrhea and are referred to as diarrhea-predominant IBS (IBS-D). Other cases still are mixed (IBS-M).

When diarrhea is involved, it can sometimes be green due to undigested bile, especially if the diarrhea is persistent or severe.

Other symptoms of IBS include:

  • Bloating
  • Indigestion
  • Gas
  • Abdominal pain
  • Whitish mucus on stools
  • Inability to empty the bowel

Non-Alcoholic Fatty Liver Disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a common disease in which fat deposits accumulate in the liver. This can damage the liver over time and lead to cirrhosis (the loss of liver function due to scarring).

NAFLD generally has no symptoms, but when it progresses to a more severe form of the disease called nonalcoholic steatohepatitis (NASH), it is likely to cause symptoms like diarrhea. In some cases, the stool may be greenish or take on more of a pale, chalky appearance.

Other symptoms of NAFLD/NASH may include:

  • Fatigue
  • Upper-right abdominal pain
  • Dark urine
  • Weight loss

Gallbladder Removal

The gallbladder is the organ that stores and concentrates bile produced by the liver. There are conditions for which the gallbladder may need to be removed in a surgical procedure known as cholecystectomy.

Indications for cholecystectomy include:

Once the gallbladder is removed, bile can flow freely into the small intestines and lead to green stools. Indigestion, flatulence, and constipation can also occur.

Green Stools in Infants, Toddlers, and Children

Green stool is a normal occurrence in breastfed infants, especially in the first days after delivery, and is no cause for alarm.

In infants, stools will gradually change to yellow and brown as the baby approaches their first birthday and more varied foods are added to the diet. For formula-fed babies, green stool may persist for several months. This is likely due to the iron content of some formulas.

In addition, giving an infant or a child an iron supplement (commonly recommended by pediatricians) may also cause green stools.

In older children, green stool may also be due to eating non-food items, such as crayons.

Treatment of Green Diarrhea

The treatment of green diarrhea varies by the underlying cause. If you don't know what caused it, speak with your primary care provider or a specialist known as a gastroenterologist. This is especially true if there are other symptoms like nausea, abdominal pain, or vomiting.

Foods and Medications

If you get green stools after eating food or taking certain medication—and don't have any other symptoms—you probably shouldn't worry all that much. But just to be safe, speak with your healthcare provider or pharmacist to ensure that this is a normal side effect.

When to See a Healthcare Provider

Persistent diarrhea, whether colored or not, should never be considered normal. If you experience chronic diarrhea, even in the absence of any other symptom, see your healthcare provider or a gastroenterologist for further evaluation.

Food Poisoning

As uncomfortable as it can be, food poisoning doesn't always require medical treatment. The key is to get plenty of fluids with electrolytes so you don't get dehydrated. Over-the-counter (OTC) anti-diarrhea medications can also help.

For more severe cases, your healthcare providers prescribe antibiotics to treat the underlying infection. In cases of severe dehydration, intravenous (IV) fluids may be needed.

Food Intolerance and Sensitivity

The most common treatment for food intolerance or sensitivity is eliminating problem foods from your diet. If you're not sure what's causing your symptoms, you may be advised to keep a food diary detailing when you had digestive symptoms and what you ate prior to them.

Your healthcare provider may also order tests to pinpoint the exact cause of your intolerance, including:

  • IgE antibody tests if celiac disease is suspected
  • Genetic tests to rule out celiac disease
  • A hydrogen breath test to detect lactose intolerance
  • Intestinal biopsy to check for changes consistent with celiac disease

Inflammatory Bowel Disease

The treatment of ulcerative colitis and Crohn's disease usually involved medications that temper the underlying inflammation that causes IBD symptoms.

Common treatments include:

Irritable Bowel Syndrome

Diarrhea-predominant IBS is mainly treated with dietary and lifestyle changes. Part of this involves the avoidance of fermentable sugars called FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) that can lead to bloating and abdominal pain.

Medications may also be prescribed in severe cases.

Treatments for IBS may include:

  • Eating more fiber and less gluten
  • A low-FODMAP diet
  • Increasing physical activity and sleep
  • Lowering stress levels
  • Anti-diarrheal medications such as Imodium (loperamide) and Xifaxan (rifaximin)
  • Drugs like Viberzi (eluxadoline) and Lotronex (alosetron) specifically licensed for IBS-D

Nonalcoholic Fatty Liver Disease

There are no medications that directly treat NAFLD or NASH. The treatment mainly involves lifestyle changes to reduce the accumulation of fat in your liver.

It may also require the management of chronic conditions closely linked to NAFLD, including high cholesterol, high blood pressure, and type 2 diabetes.

The treatment of NALFD/NASH may include:


Following gallbladder removal, dietary and lifestyle changes will invariably be needed to aid with digestion. While the gallbladder isn't essential to digestion, the absence of this tiny organ can lead to digestive symptoms unless your diet is controlled.

This usually involves:

  • A low-fat diet high in soluble fiber
  • Avoiding fatty foods, such as fried foods
  • Eating small, frequent meals to avoid overstressing the intestines
  • Bulking agents like Metamucil (psyllium) to normalize bowel movements
  • Imodium (loperamide) to treat occasional diarrhea

When to Call a Healthcare Provider

Irrespective of its color, diarrhea can turn serious if it persists and is left untreated. Call your healthcare provider immediately if you have:

  • Diarrhea for longer than three days
  • Diarrhea accompanied by vomiting for longer than 24 hours
  • Severe abdominal or rectal pain
  • Signs of dehydration, such as sunken eyes, dizziness, confusion, or difficulty peeing
  • Bloody diarrhea

Sometimes a stool will have a blackish hue that may also look a bit greenish. In absence of a reasonable cause (such as taking iron supplements or Pepto-Bismol), it is important to see your healthcare provider anytime you have black or tarry stools.

A black stool is often an indication of intestinal bleeding (the blood of which will increasingly darken and turn black as it moves down the intestinal tract). Black stools could be a sign of an ulcer or a more serious concern like colon cancer. Early diagnosis of these conditions almost invariably leads to better outcomes.


Green diarrhea or stool is unusual but not typically something to worry about. The most common cause of green stool is diet. Eating green, blue, or purple foods is often the culprit—especially when they contain food dyes. 

Several medical conditions can cause green diarrhea. Many of them involve rapid digestion, which makes bile retain its green color instead of turning brown. Causes include food poisoning, food intolerance, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and gallbladder removal.

Frequently Asked Questions

  • Why would I have green poop during pregnancy?

    Green poop is somewhat common in the earliest weeks of pregnancy, during the third trimester when digestion speeds up, and if you take iron supplements or prenatal vitamins. It can also be due to food, especially if you've increased your consumption of green or purple vegetables.

  • Can COVID-19 cause green poop?

    Yes, it can. COVID-19 can impair the way fat is broken down in your digestive system. Fatty stools may look yellow or, if there's a high bile content (which is common), green.

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By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.