Black and Watery Stool: Causes and Concerns - Gastroenterology and Hepatology

Black, loose stools?

Hello, doctor.
This afternoon, I experienced a strong urge to have a bowel movement.
Upon passing stool, I noticed that the odor was different from usual, having a tar-like smell.
When I stood up, I saw that most of the stool was black and somewhat loose, floating on the surface (based on the Bristol Stool Chart, I would estimate it to be around type 6), with a small amount of brown stool (approximately type 5) stuck beneath the black stool.
I felt that something might be wrong, so I wanted to ask for advice.

Before and after passing the black stool, I did not notice any other unusual symptoms.
I usually have a bowel movement once a day.
Yesterday, I had a slight gastrointestinal discomfort and had a bowel movement in the afternoon, and then another before taking a shower in the evening, both of which were normal in color and consistency.
However, I have been experiencing some coccyx pain lately, and I'm not sure if this is related; it might be due to poor sitting posture.
Additionally, I usually drink a cup of vitamin effervescent daily.
Today at noon, I had fresh milk tea at a brunch place, which I believe might be the main cause, but I am still feeling uneasy, so I wanted to consult you.

Zhao Hanjie, 20~29 year old female. Ask Date: 2022/09/26

Dr. Chen Shidian reply Gastroenterology and Hepatology

If you have loose stools, be cautious with low-fat dairy products and continue to monitor your condition.
If you notice black stools resembling the color of black hair, seek medical attention immediately.

Reply Date: 2022/09/26

More Info

Black and watery stools can be concerning and may indicate underlying health issues that require attention. The characteristics you've described—black, tarry stools with a foul odor—are often associated with gastrointestinal bleeding, particularly from the upper gastrointestinal tract. This could be due to various causes, including but not limited to peptic ulcers, gastritis, or even esophageal varices. The presence of black stools, medically termed "melena," suggests that the blood has been digested, which typically occurs when bleeding is from a higher point in the digestive system.

The fact that you also mentioned experiencing tailbone pain could be related to your sitting posture, but it is essential to note that it may not directly correlate with the changes in your stool. However, if you have been experiencing discomfort in the lower back or tailbone area, it might be worth considering whether any changes in your activity level or posture could be contributing to both the pain and your gastrointestinal symptoms.

Your recent dietary habits, including the consumption of fresh milk tea and vitamin supplements, are unlikely to be the primary cause of black stools. However, certain foods and medications can cause changes in stool color. For instance, iron supplements and certain foods like black licorice can lead to darker stools. If you have recently started any new medications or supplements, it would be prudent to review these with your healthcare provider.

Given the symptoms you've described, it is crucial to seek medical attention promptly. A healthcare professional will likely recommend a thorough evaluation, which may include a physical examination, a review of your medical history, and possibly diagnostic tests such as blood tests, stool tests, or imaging studies. These assessments can help determine the cause of your symptoms and guide appropriate treatment.

In the meantime, monitor any additional symptoms that may arise, such as abdominal pain, changes in appetite, weight loss, or any signs of anemia (like fatigue or pallor). If you experience any severe symptoms, such as vomiting blood or experiencing dizziness, seek emergency medical care immediately.

In summary, while occasional changes in stool color can occur due to dietary factors or minor gastrointestinal disturbances, the combination of black, watery stools and a foul odor warrants further investigation to rule out serious conditions. It is always better to err on the side of caution when it comes to gastrointestinal health, so please consult a healthcare provider as soon as possible for a comprehensive evaluation.

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