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A change in stool color can cause concern, especially if a green tint appears. In most cases, green stool in adults occurs due to changes in diet or particular features of the digestive system. However, sometimes such a change may be a sign of infection or an inflammatory process. It is important to pay attention not only to the color but also to overall well-being, the presence of abdominal pain, fever, or bowel disturbances.

In this article, we will examine why stool may be green, in which cases this is a physiological reaction of the body, and when it is a symptom of disease. Understanding the possible mechanisms helps to distinguish harmless changes from conditions that require diagnosis and treatment in a timely manner.

What Does Green Stool Mean in Adults

The color of stool is formed under the influence of bile — a fluid produced by the liver to digest fats. Normally, bile pigments change their shade as they pass through the intestines, and the stool becomes brown. If this process occurs more quickly or is disrupted at a certain stage, a green tint may appear.

Green stool does not always indicate pathology. Sometimes it is the result of accelerated intestinal transit, when bile does not have time to fully transform. In such cases, the green color of the stool is associated with physiological changes rather than disease.

At the same time, it is important to assess the situation comprehensively. If the color change is combined with abdominal pain, fever, diarrhea, or general weakness, this may indicate digestive disorders, an infectious process, or inflammation of the intestinal mucosa. In such cases, a consultation with a gastroenterologist is necessary.

Common Causes of Green Stool

Most often, causes of green stool are related to dietary habits, the speed at which food passes through the intestines, or inflammatory changes in the mucosa. To properly assess the situation, it is important to understand which mechanisms can affect stool color and when caution is warranted.

 

Dietary Causes of Green Stool

Most commonly, a change in shade is related to diet. Green stool — causes of dietary origin may include:

  • consuming large amounts of green vegetables (spinach, broccoli, leafy greens);
  • consuming foods and beverages with bright food colorings;
  • taking dietary supplements or vitamin complexes;
  • a sudden change in diet or dietary experiments.

In such cases, stool color usually returns to normal on its own after dietary adjustments. At the same time, overall well-being does not worsen, and there is no abdominal pain, fever, or pronounced diarrhea.

Digestive Disorders and Impaired Bile Absorption

Bile pigments play a key role in forming the normal brown color of stool. If food passes through the intestines too quickly, bile does not have time to fully transform, and the stool may take on a greenish tint.

Such changes are possible with functional intestinal disorders, irritable bowel syndrome, or motility disturbances. Sometimes the cause is problems with fat digestion or impaired bile outflow. In these cases, it is important to pay attention to accompanying symptoms — bloating, discomfort after eating, and unstable bowel movements.

Infectious and Inflammatory Causes of Green Stool

Bacterial or viral infections of the gastrointestinal tract can change not only the frequency of bowel movements but also their color. When the intestinal mucosa is inflamed, normal absorption and digestion are disrupted, which affects the shade of the stool.

In such situations, liquid green stool often appears, combined with abdominal pain, fever, or general weakness. These symptoms require careful attention, as they may indicate an acute infectious process or inflammatory bowel disease.

If the changes persist for several days or are accompanied by worsening well-being, it is advisable to consult a doctor to determine further examination and treatment tactics.

Dark Green Stool in Adults

The shade of stool can vary from light green to a deep dark color. It is the deep, almost swamp-like or olive tone that most often causes concern. It is important to understand that the intensity of the color also matters and is assessed together with stool consistency and the person’s overall condition.

What Does Dark Green Stool Mean

A dark green shade may be associated with a high concentration of bile pigments that have not yet changed their color during digestion. This sometimes occurs with accelerated intestinal peristalsis or after consuming a significant amount of dark green pigmented foods.

This color may also occur when bile combines with certain food components or supplements. If the stool remains formed, without mucus or blood impurities, and overall well-being is not impaired, it most often does not indicate a serious pathology.

At the same time, a dark shade may appear with impaired fat digestion or an imbalance of the intestinal microflora. In such cases, the color is accompanied by a change in odor, abdominal bloating, or unstable bowel movements.

When Dark Green Stool Is a Dangerous Symptom

A dark green shade requires special attention if it is combined with worsening well-being. In such cases, it is important to assess not only the color but also accompanying symptoms.

Urgent medical evaluation is required when the following are observed:

  • intense or increasing abdominal pain;
  • elevated body temperature;
  • frequent loose stools or signs of dehydration;
  • nausea or repeated vomiting;
  • sudden weakness, dizziness;
  • the appearance of mucus or other impurities in the stool;
  • persistence of dark green color for more than several days without an obvious cause.

This combination of symptoms may indicate an intestinal infection, a pronounced inflammatory process, or dysfunction of the biliary system.

In such cases, the doctor may prescribe laboratory tests as well as instrumental examinations, including abdominal ultrasound, to assess the condition of the liver, gallbladder, and intestines. Timely diagnosis helps determine the cause of the changes and define further treatment tactics.

Liquid Green Stool

A change not only in color but also in stool consistency always requires more careful evaluation. If liquid green stool appears, it most often indicates accelerated passage of intestinal contents. In this situation, bile does not have time to change its natural green shade to brown, and impaired fluid absorption leads to diarrhea.

However, it is important to consider the duration of the condition, the frequency of bowel movements, and overall well-being. A short-term episode may be a reaction to dietary irritants, whereas prolonged diarrhea with mucus, pain, or fever requires examination.

Causes of Liquid Green Stool

Loose greenish stools may occur for various reasons — from functional disorders to infectious processes. The most common include:

  • acute intestinal infections of bacterial or viral origin;
  • food poisoning;
  • a reaction to poor-quality food or a change in diet;
  • microflora disturbances after antibiotic therapy;
  • exacerbation of chronic inflammatory bowel diseases.

In most cases, the key mechanism is accelerated peristalsis and inflammation of the mucosa, which disrupt normal digestion and absorption.

Abdominal Pain and Green Stool: Possible Diagnoses

The combination of abdominal pain and a change in stool color always requires a more thorough assessment. If abdominal pain and green stool occur simultaneously with diarrhea, fever, or nausea, this may indicate:

  • acute intestinal infection;
  • gastroenteritis;
  • inflammation of the small or large intestine;
  • foodborne toxic infection.

The nature of the pain also matters. Cramping pain with frequent bowel movements is more often associated with an infectious process, whereas prolonged aching discomfort may indicate inflammatory or functional disorders.

If symptoms do not decrease within 1–2 days, the condition worsens, or signs of dehydration appear, medical examination is necessary. In complex cases, the doctor may recommend endoscopic evaluation of the upper digestive tract, including gastroscopy, to exclude concomitant pathology and clarify the cause of the disorder.

If Stool Is Green: When to See a Doctor

In most cases, a change in stool color is temporary and related to diet or functional особенностями пищеварения. However, there are situations when medical consultation is necessary.

You should consult a specialist if:

  • the green shade persists for more than several days without an obvious cause;
  • frequent diarrhea appears;
  • abdominal pain occurs that does not go away or intensifies;
  • body temperature increases;
  • nausea or repeated vomiting is observed;
  • signs of dehydration appear (dry mouth, weakness, infrequent urination);
  • mucus or other pathological impurities are noticeable in the stool.

People with chronic gastrointestinal or biliary diseases should be especially attentive, as their risk of complications is higher.

Examination and Diagnosis for Green Stool

The examination strategy depends on the clinical picture, the duration of symptoms, and the patient’s overall condition. The doctor уточняет особенности питания, наличие сопутствующих заболеваний, характер боли и изменений стула.

The main diagnostic methods include:

  • a complete blood count to detect an inflammatory process;
  • stool analysis to exclude infection or microflora disturbances;
  • blood tests to assess liver and biliary function;
  • instrumental methods, including abdominal ultrasound.

In complex cases, the doctor may recommend endoscopic evaluation of the upper digestive tract, including gastroscopy, to exclude concomitant pathology and clarify the cause of the disorder.

Timely diagnosis makes it possible to determine the exact cause of the changes, select treatment, and prevent complications. If the color change is combined with worsening well-being, examination should not be postponed.

The information in this article is provided for informational purposes only and is not intended as a guide to self-diagnosis or treatment. If symptoms of the disease appear, consult a doctor.

Sources:

US National Library of Medicine (MedlinePlus – Stool Color Changes)

National Institutes of Health (NIDDK – Diarrhea and Digestive Diseases)