Causes, Related Symptoms, and What to Do

Green Diarrhea Causes
Foods	Medications	Conditions
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	Metabolic dysfunction-associated steatotic liver disease (MASLD)
Alcohol		Medical Procedures (gallbladder removal, bone marrow transplant)

For instance, certain foods can add a greenish hue to a stool. Additionally, some foods can have a laxative effect that speeds up digestion, resulting in diarrhea.

Under normal circumstances, bile turns 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 That Cause Green Diarrhea

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.

Green stools are most frequently seen 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
• Alcohol
• Fructose (a sugar in fruit)
• Spicy foods (this is due to capsaicin, found in many peppers)

Medications That Cause Green Diarrhea

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.

Medical Conditions That Cause Green Diarrhea

Several medical conditions 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 occurs when the body has an abnormal reaction to food, causing it to rid itself of the food as quickly as possible. Green, watery stool, along with bloating, nausea, and abdominal cramping, is a possible symptom.

Some of the causes are autoimmune, meaning that the immune system mistakenly attacks the lining of the intestines by releasing an antibody known as immunoglobulin E (IgE). Allergens react with IgE, releasing chemicals that cause various symptoms throughout the body.

Other causes of intolerance involve various immune cells without the influence of IgE. Non-IgE food intolerances and sensitivities can take longer for symptoms to show, often making diagnosing the cause more challenging.

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 the digestive system. The cause of IBD is unknown, but it is thought to result from genetics, a weakened immune system, and environmental triggers such as viruses or bacteria.

Diarrhea is a common symptom of both ulcerative colitis and Crohn’s disease. The diarrhea color can vary from 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. Several factors are thought to cause IBS, 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

Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD; formerly known as nonalcoholic fatty liver disease or 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).

MASLD generally has no symptoms, but when it progresses to a more severe form of the disease called metabolic dysfunction-associated steatohepatitis (MASH; formerly known as nonalcoholic steatohepatitis or 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 MASLD/MASH 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. In certain conditions, 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, leading to green stools. Indigestion, flatulence, and constipation can also occur.

Sometimes, individuals wonder if liver issues can cause green diarrhea since the liver is involved in bile production. However, gallbladder issues are much more likely to cause green diarrhea than liver issues. Instead, those with liver damage are much more likely to experience blood in their stool than green stools.

Bone Marrow Transplant Complications

One of the primary uses for a bone marrow transplant is part of cancer treatment, particularly cancers that affect bone marrow function. Examples of these cancers include certain leukemias, multiple myeloma, and lymphomas.

Bone marrow transplants work by helping to replace blood cells that are lost during treatments like chemotherapy and by growing healthy, cancer-free blood cells.

While bone marrow transplants are part of a successful treatment plan for many patients, sometimes there are complications. The three main complications that all include diarrhea as a symptom are:

Infection: The highest risk for infection is typically during the first six weeks after a transplant. Symptoms can include fever, cough, shortness of breath, and diarrhea.

Acute graft vs. host disease (GVHD): This condition may occur ten to 90 days after the transplant. The most common period is around day 25. The first symptom is typically a rash that starts on the palms of the hands and soles of the feet and then may spread. Several additional GI symptoms, including diarrhea, may also develop.

Chronic graft vs. host disease (GVHD): The chronic version of GVHD happens between 90-600 days after the stem cell transplant. This condition is associated with several symptoms, including diarrhea, other GI symptoms, liver involvement, mouth sores, and skin manifestations.

Gastrointestinal Cancers

Various cancers can cause diarrhea as a symptom. These cancers include:

• Pancreatic
• Gastric
• Colorectal

Other cancer types may also cause diarrhea, but these are the most likely to do so. If you experience any changes in your bowel habits, such as diarrhea, contact your healthcare provider.

Additionally, diarrhea may be a side effect of treatments and therapies, such as:

• Chemotherapy
• Immunotherapy
• Targeted drug therapy
• Radiation therapy

Diarrhea may also present as a symptom of complications during cancer treatment, such as:

• Infections (e.g., Clostridioides difficile and neutropenic enterocolitis)
• Small bowel obstruction
• Graft vs. host disease

If you are undergoing cancer treatment and experience diarrhea, reach out to your healthcare provider. They may want to run various tests to rule out any complications.

Green Stools in Infants, Toddlers, and Children

Green stool is normal in breastfed infants, especially in the first days after delivery, and is not 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.

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

If you notice a change in your child’s bowel habits, such as green diarrhea, and are concerned, contact your healthcare provider or their nurse line for advice.

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 experience green diarrhea after eating food or taking certain medication and don’t have any other symptoms, then the food or medications are likely to blame. However, if the green stools are new, speak with your healthcare provider or pharmacist to ensure this is a normal side effect.

Food Poisoning

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

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

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, 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:

• 5-aminosalicylic acid (5-ASA), a class of anti-inflammatory drugs that includes Salazopyrin (sulphasalazine), Mezavant (mesalazine), and Dipentum (olsalazine)
• Immunomodulators, a class of drugs that suppress the immune system and include agents like methotrexate, Imuran (azathioprine), and Purinethol (6-mercaptopurine)
• Corticosteroids, also known as steroids, that temper the overall immune response and include drugs like prednisone and Entocort (budesonide)
• Biologic drugs, a class of medications that suppress specific parts of the immune system and include drugs like Humira (adalimumab), Cimzia (certolizumab), and Remicade (infliximab)

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

Metabolic Dysfunction-Associated Steatotic Liver Disease

Rezdiffra (resmetirom), combined with diet and exercise, is the only FDA-approved medication to treat MASH.

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

The treatment of MASLD/MASH may include:

• Weight loss
• A low-fat diet plan
• Routine exercise
• Avoidance of alcohol
• Quitting cigarettes
• Antihypertensive drugs to lower your blood pressure
• Statin drugs to lower your cholesterol
• Metformin to lower your blood sugar
• Rezdiffra (resmetirom)

Cholecystectomy

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

Bone Marrow Transplant Complications

If a bacterial infection is causing diarrhea, your provider will likely start you on an antibiotic.

Acute GVHD may be treated with only a topical steroid. However, more severe cases of acute GVHD and cases of chronic GVHD are treated with oral or injected steroids. Sometimes, additional immunosuppressive drugs are needed.

Gastrointestinal Cancers

Treatment for diarrhea related to gastrointestinal cancers depends on the cause. If the diarrhea is due to a newly diagnosed cancer, treating the cancer may eventually resolve the diarrhea.

If diarrhea is due to cancer treatment, let your healthcare team know. Depending on the severity, they may adjust your treatment schedule. Or there may be medications you can take to help.

Diarrhea is also a symptom of an infection or GVHD. So be sure to inform your healthcare provider about any diarrhea, especially if it is combined with a fever. If you have an infection, you may need antibiotics. Additionally, for GVHD, your provider may prescribe steroids or other immunosuppressive drugs.

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 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, stools have a blackish hue that may also look a bit greenish. In the 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.

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.

Summary

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.