Green Diarrhea: 7 Common Causes & What to Do

Medical review: Dr. Gonzalo Ramirez
General Practitioner and Psychologist
September 2022

Green diarrhea can occur after eating excess dark green vegetables, after drinking coffee, or after eating spicy food. These foods in particular have laxative effects which can decrease the absorption of water in the intestines, leading to diarrhea. These foods also increase intestinal flow, which interferes with the function of bile. Bile is a green substance produced in the liver that is undergoes a reaction with intestinal bacteria, and gives the stool a brown color. 

Green diarrhea can also be a sign of a health problem, like an intestinal infection, irritable bowel syndrome or Crohn’s disease. These conditions will often be accompanied by other symptoms, like excess gas, abdominal swelling, fever or loss of appetite. 

Treatment for green diarrhea involves plenty of fluid intake, taking electrolytes and probiotics, and determining the underlying cause of the problem. If green diarrhea lasts for more than 2 days, or if you experience other symptoms like abdominal pain, nausea, or vomiting, you should see your doctor for assessment and treatment as necessary. 

The main causes of green diarrhea are:

1. Eating too many dark green vegetables  

Dark green vegetables like broccoli, cabbage, chard, arugula or spinach are rich in fiber which promote intestinal flow. They can help to relieve both constipation or diarrhea. However, when consumed in excess, they can make stool for soft or liquid, leading to diarrhea. The green color comes from the concentrated levels of chlorophyll, a pigment found in the vegetable leaves. 

What to do: Diarrhea caused by excess vegetables usually resolves within a day or two of removing these from the diet. This type of diarrhea is not usually concerning. You should aim to keep the body well-hydrated, and if your diarrhea does not improve, you should see a doctor for assessment to rule out another cause. 

2. Excessive intake of coffee, alcohol or spicy food 

Excessive intake of coffee, alcohol or spicy food can speed up digestion and cause a laxative effect. This leads to more liquid stools and diarrhea. Because of the faster flow, bile does not have enough time to become brown, which gives the stool a green color. 

What to do: You should consume these foods in moderation and in small quantities to prevent the laxative effect. This also allows bile to have time to act properly in the intestine. 

See what else can cause green poop.

3. Using iron supplements  

Using oral iron supplements for treatment of anemia, for example, can change stool color and give them a darker color. This means the body is absorbing iron adequately. 

Nonetheless, when iron supplements are not completely absorbed in the intestine, you may experience diarrhea that is dark green or black as a side effect.

What to do: You should see your doctor to evaluate your treatment and the need for an alternative method of supplement, such as an IV infusion. 

4. Using laxatives

Using laxatives speeds-up intestinal flow, which decreases absorption of water in the intestine. This leads to more liquid stools and diarrhea. 

The green color is caused by the presence of undigested bile. Bile is usually brown-green in color and produced in the liver. Its main function is to breakdown fat from food, and in gradually changes to a brown color as it goes further through the intestinal tract. 

Therefore, excessive or prolonged use of laxatives will lead to liquid stool and built-up bile.

What to do: Stopping your laxative use will allow the stool to return to its normal color in 2 to 3 days. If your symptoms do not improve, however, or if you have other symptoms like intense abdominal cramping, nausea, vomiting, stomach ache, or bloody stools, you should see your doctor or proceed to the hospital. 

5. Intestinal infections

Green diarrhea can also be a sign of intestinal infections caused by Salmonella sp or by Giardia lamblia bacteria. Salmonella sp, infections are normally caused by food contaminated by this bacteria, and green diarrhea is a common symptom, as well as nausea, vomiting, abdominal pain, fever, bloody stools, headache and muscle aches.  

Giardiasis is an infecion caused by a parasite known as Giardia lamblia that is transmitted through contaminated water.In addition to liquid green diarrhea, you may experience other symptoms like gas, abdominal pain or swelling, fever, nausea, vomiting, loss of appetite and dehydration. Learn more about symptoms of an intestinal infection

What to do: You should ensure you are drinking plenty of fluids to maintain your hydration status, as diarrhea can lead to moderate water losses. If your diarrhea does not improve, you should see your doctor, who may prescribe antibiotics and reccomend additional home remedies for an intestinal infection

6. Using antibiotics 

Using antibiotics, like cephalosporins or penicillins, can cause imbalances in bacteria that naturally occur in the intestines. This can interfere with the absorption of water and nutrients, leaving stool softer or liquid. 

Good bacteria in the intestines are also responsible for bile digestion. When bile is not adequately used by these bacteria, it remains green in color, leading to green stools.

What to do: You should not stop taking your antibiotics without your doctor’s knowledge. Therefore, you should contact your doctor and inform him/her if you have diarrhea. When taking antibiotics, you should maintain adequate hydration by drinking 8 cups of water per day. In addition, consuming probiotics may help to regulate intestinal bacteria and improve green diarrhea.   

7. Irritable bowel or Crohn’s disease 

Some people with intestinal conditions, like Crohn’s disease, irritable bowel syndrome or ulcerative colitis may experience green diarrhea. This is due to the poor digestion of fat and the inflammation long the intestinal mucosa. These conditions are associate with symptoms like abdominal pain or excess gas.  

In addition, people who hae removed their gallbladder may also experience green diarrhea. This happens because bile that is produced by the liver is no longer stored in the gallbladder, and goes directly to the intestines, giving stool a green color. 

What to do: You should follow treatment as indicated by your doctor, making sure to follow an appropriate diarrhea as recommended by a registered dietitian. This can help to prevent worsening of diarrhea or other symptoms. 

Green diarrhea during pregnancy 

Green diarrhea during pregnancy mainly occurs due to prenatal supplements that contain iron. It is generally not a concerning symptoms. You should continue to take your vitamins in the doses recommended by your doctor and drink at least 8 cups of water per day.

In the meantime, if your green diarrhea does not improve within 3 dyas, or if it is accompanied by fever, nausea, vomiting, back pain, right-sided abdominal pain, cramping, or abdominal swelling, you should seek medical attention immediately. 

Green stool in babies 

In the first 2 or 3 days following birth, it is normal for babies to have soft, sticky, mucus stool that is black or green. This stool is called meconium, and it consists of the substances that were released by the intestine during pregnancy. 

After 3 to 5 days of life, babies will go through a transition phase in their stool due to breastmilk, and will obtain a more brown color by their sixth day of life. Babies who are fed with formula may continue to have green stools for longer, likely due to the iron found in formulas.

In older babies, green stool may be a sign of an infection, a food intolerance, the presence of bile, medication or from eating green fruits or vegetables. 

When to see the doctor 

You should see your doctor if your green stool persists for more than 3 days, or if you have symptoms like: 

  • Nausea or vomiting 
  • Abdominal pain 
  • Stomach pain 
  • Fever
  • Bloody stools
  • Mucus in stools 

You should seek immediate medical attention if you have symptoms of dehydration like dark urine, a dry or sticky mouth, excessive fatigue, dizziness, headache, confusion or fainting. 

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Atualizado por Tua Saude editing team, em September de 2022. Medical review por Dr. Gonzalo Ramirez - General Practitioner and Psychologist, em September de 2022.

References

  • DEN, HERTOG; et al. The Defecation Pattern of Healthy Term Infants up to the Age of 3 Months. Arch Dis Child Fetal Neonatal. 97. F465-70, 2012
  • TAN, C. K.; CHAO, C. M.; LAI, C. C. Green feces. QJM. 106. 3; 287, 20113
Show more references
  • LANFER-MARQUEZ, Ursula Maria. O papel da clorofila na alimentação humana: uma revisão. Revista Brasileira de Ciências Farmacêuticas. 39. 3; 227-242, 2003
Medical review:
Dr. Gonzalo Ramirez
General Practitioner and Psychologist
Dr. Ramirez possesses a medical degree from the Universidad Popular Autónoma del Estado de Puebla (UPAEP). He also specializes in clinical psychology.