Green Diarrhea: What It Means & When It’s Serious

Key takeaways:

• Green diarrhea can be the result of several causes, including your diet, bile in your intestinal contents, or a possible infection in your GI system. Most often green diarrhea is a short-lived condition and goes away on its own.
• A bout of green diarrhea could mean you have a more serious condition if you also have symptoms like stomach pain, fever, or vomiting. Knowing when you should go for medical care is important.
• Knowing how to manage green diarrhea at home, as well as understanding when you need medical attention, can help you prevent more serious problems like dehydration.

Seeing green diarrhea when you go to the toilet can be startling, especially if it occurs suddenly. The color and consistency of your stool is influenced by a lot of different factors, and can range from something as simple as what you had for dinner to a medical problem.

Let’s explore the common causes of green diarrhea, what its appearance might mean, and help you understand when you should get medical advice. Whether your green diarrhea is caused by something as simple as eating a lot of leafy greens or is a sign of an intestinal infection, understanding possible causes will help you know how to manage this symptom.

Is green diarrhea normal?

Green diarrhea isn’t necessarily a cause for alarm, as it can result from eating certain foods or taking supplements that affect your stool color.

But if green diarrhea lasts for several days or you also have other symptoms, there might be an underlying problem. Understanding what may be behind the color change is the key to deciding whether or not you need medical care.

Common causes of green diarrhea

Green diarrhea can result from several different causes, and these are important to understand so you can get treatment if needed. Below are some common causes of green-colored stool:

Dietary causes

One of the most common reasons for having green diarrhea is eating green-colored foods. Leafy greens like spinach, kale, turnip and collard greens contain the green pigment chlorophyll, which can affect the color of your stool. Artificial food coloring, commonly found in some candies, ice creams, and in many processed foods can also be the culprit in causing green stools.​

Bile production

Bile is a greenish fluid produced by your liver that helps your body digest fats. Much of the bile that is produced is stored in your gallbladder, and is then released as needed into the upper part of your small intestine.

As bile moves through your digestive system, it usually turns yellow or brown. But when food passes too quickly through your intestines, such as during a bout of diarrhea, the bile doesn’t have enough time to change color and this can result in green stool​. Problems with bile acid metabolism can also trigger green diarrhea.

Gastrointestinal infections

Infections such as food poisoning caused by bacteria (such as salmonella or giardia), or a stomach flu due to a norovirus can lead to green diarrhea.

These infections often cause diarrhea because your body is trying to get rid of the harmful bacteria or virus quickly, resulting in intestinal contents that have not had enough time to be fully processed​.

Medications and supplements

Certain medications, such as some antibiotics, or supplements like iron, can affect your stool color as well as its consistency. These substances may cause your digestive system to process bile more rapidly, which can lead to green diarrhea. Or they may actually color the stool directly, as in the case of iron.​

Read our guide on common causes of diarrhea for more.

What green diarrhea may mean based on appearance, consistency, or another symptom or condition

The appearance of green diarrhea can offer you some clues as to the reason behind it. Here's what different types of green diarrhea may mean:

Bright or lime green diarrhea

Bright green diarrhea is often linked to the presence of green food dyes or a high intake of green vegetables. This may also be a sign that food is passing very quickly through your intestines.

Green, watery or liquidy diarrhea

Green, watery diarrhea may indicate a possible infection, such as from food poisoning or stomach flu (gastroenteritis). Rapid movement of stool through your intestines is a common cause of this symptom.

Black-green or very dark green diarrhea

A dark green stool could be the result of taking iron supplements or eating foods with artificial coloring.

But use caution here. If your stool is blackish-green in color, this could mean bleeding in your upper gastrointestinal tract (esophagus, stomach or the upper part of your small intestine). If black-green or very dark green stool is present, you should get medical advice.

Green diarrhea with mucus in the stool

Mucus in your stool can indicate possible inflammation in your intestines. Inflammation could be due to an infection, irritable bowel syndrome (IBS), or another inflammatory condition affecting your bowels.

Green diarrhea with a foul odor

When green diarrhea has an especially foul odor, it could be a sign of a bacterial or parasitic infection. Common culprits include Salmonella (usually from contaminated food) or Giardia (most often contracted by drinking contaminated water).

Green diarrhea accompanied by stomach pain or cramps

If you have green diarrhea along with stomach cramps, this is another sign you might have a gastrointestinal infection or food poisoning.

Green diarrhea accompanied by vomiting

If you’re experiencing both green diarrhea and vomiting, you might have a stomach infection or a foodborne illness. It’s very important to keep up your fluid intake and consult a doctor if your symptoms don’t get better.

Green diarrhea experienced immediately after eating

Green diarrhea directly after eating may be an issue with the processing of bile or very rapid digestion. If this occurs frequently, it could be that you have an underlying digestive problem.

Green diarrhea after drinking alcohol

Alcohol is a very well known irritant to the digestive system. This irritation can lead to faster passage of stool, which can result in green diarrhea. Regular alcohol use can also affect your liver function, and this can cause bile-related color changes to your stool.

Green diarrhea that occurs during a pregnancy

Pregnancy, with its multitude of hormonal changes, can sometimes result in changes to your bowel movements. These can include green diarrhea. In some cases, if you are taking prenatal vitamins containing iron, this may be the cause​.

When to see a doctor about green diarrhea

While green diarrhea is often harmless, there are certain times when medical care is necessary.

You should see a doctor if:

• Your green diarrhea lasts longer than a few days.
• You have green diarrhea along with symptoms like fever, severe stomach pain, or you can’t keep liquids down.
• There is blood or mucus in your stool.

You should go to the emergency room if:

• Along with green diarrhea you are also having significant vomiting or signs of severe dehydration, such as a dry mouth, dizziness, reduced urination or your urine becomes dark and has a strong odor.
• You experience a black-green stool, which might indicate bleeding.

Questions to ask your doctor about green diarrhea

To make the most of your doctor's visit, consider asking the following questions:

1. What could be causing my green diarrhea?
2. Do I need any tests to diagnose the cause of my symptoms?
3. What treatments or dietary changes can help to reduce my symptoms?
4. How can I prevent green diarrhea from happening again?

How to stop or treat green diarrhea

Treatments for green diarrhea will depend on the cause of your condition, but here are some general guidelines for you to follow:

Stay hydrated

If your diarrhea continues, it’s essential that you replace lost fluids. Oral rehydration solutions such as various sports drinks, PediaLyte,™ or clear fluids like water or broth are ideal.

Avoid trigger foods

If you suspect that your diet is the cause of your green diarrhea, try avoiding green vegetables, artificial dyes, or foods you know will likely upset your digestive system.

Take over-the-counter medication

Taking over-the-counter antidiarrheal medications like loperamide (such as brand name Imodium A-D) can help to slow your bowel movements and reduce symptoms. If you suspect you might have an intestinal infection, you should consult your doctor before taking these types of medications. ​

Read our guide on how to get rid of diarrhea for more.

How to prevent green diarrhea

The prevention of green diarrhea can include choosing which foods you eat and careful attention to hygiene practices during food preparation:

Practice good hand hygiene

You should wash your hands thoroughly before eating or preparing food to prevent gastrointestinal infections.

Cook food thoroughly

Be sure all meats are cooked to safe temperatures to avoid foodborne illnesses that may cause green diarrhea. Meat such as steaks, chops and roasts should be cooked until their internal temperature reaches 145 degrees F. Poultry and other fowl should be cooked to 165 degrees F and eggs and ground meat to 165 degrees F. Use a cooking thermometer to determine when the food is safely done, rather than simply relying on the how the food looks to you.

Avoid foods that may cause green diarrhea

Again, because many cases of green diarrhea can be traced back to certain foods, avoid eating large amounts of green vegetables, candies or other processed foods colored with green dyes, or supplements that may cause green colored stools.

Stay hydrated

Drinking plenty of fluids can help you to maintain regular bowel movements and potentially prevent issues like bile processing problems.

Frequently asked questions: green diarrhea

Does green diarrhea mean you have liver problems?

Green diarrhea does not necessarily mean you have a liver problem. But if you have chronic diarrhea or you suspect a bile-related problem, you should discuss your liver function with your doctor.​

Why is your poop green, even though you didn’t eat anything green?

Green poop may be the result of bile, a greenish digestive fluid made by your liver and stored in your gallbladder, that hasn’t had enough time to break down in your digestive system due to rapid passage through your gut.

What if you’ve had watery, green diarrhea for two days or more?

Diarrhea which lasts two or more days may mean you have an intestinal infection or other gastrointestinal issues. You should get medical care if your symptoms last longer than two days or you have additional symptoms such as abdominal pain, fever or vomiting.

Managing green diarrhea

Green diarrhea can often be a temporary and harmless condition, but it can also be a symptom of a more serious problem. It’s important to understand the potential causes and also know when you should get medical attention. If your green diarrhea continues more than a couple of days or you have other concerning symptoms, you should consult your healthcare provider.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Lane Thaut, DO.

Sources

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Minnesota Department of Health. "Cooking and Food Temperature: Safe Minimum Cooking Temperatures." Minnesota Department of Health, https://www.health.state.mn.us/people/foodsafety/cook/cooktemp.html. Accessed 22 Oct. 2024.

National Institute of Diabetes and Digestive and Kidney Diseases. "Viral Gastroenteritis." National Institute of Diabetes and Digestive and Kidney Diseases, https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis. Accessed 22 Oct. 2024.

Nguyen, M., and P. Tadi. "Iron Supplementation." StatPearls, updated 3 July 2023, StatPearls Publishing, 2024. https://www.ncbi.nlm.nih.gov/books/NBK557376/. Accessed 22 Oct. 2024.

Vijayvargiya, Priya, et al. "Current Practice in the Diagnosis of Bile Acid Diarrhea." Gastroenterology, vol. 156, no. 5, 2019, pp. 1233-1238. https://www.gastrojournal.org/article/S0016-5085(18)35400-3/fulltext. Accessed 22 Oct. 2024.