Gastrointestinal Disorders 2022

Dark or black stools: 6 causes (and what to do)

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Dark or black stools: 6 causes (and what to do)
Dark or black stools: 6 causes (and what to do)

Dark or black stools usually appear when there is digested blood in the composition of the poop and, therefore, can be an important sign of bleeding in the initial part of the digestive system, especially in the esophagus or stomach, caused by ulcers or varicose veins.

However, dark or black stools can also appear in other less worrisome situations, such as when you are on a diet rich in iron, when you are taking iron supplements or when you are using some specific types of medicines.

Still, whenever the stool remains dark for more than 2 days, it is important to consult a gastroenterologist for stool exams or a colonoscopy, for example, to identify the cause and initiate appropriate treatment.

Learn about other poop color changes and their common causes.

The most common causes of dark stools include:

1. Intake of foods rich in iron

Making a diet very rich in foods such as beans, red meat or beets increases iron levels in the body, causing the intestine not to absorb all the iron available in food, being eliminated in the feces and causing a dark color.

However, dark stools that occur due to excessive ingestion usually do not have a foul smell, such as stools that are darkened due to the presence of blood, for example.

What to do: you should avoid excessive intake of foods rich in iron and observe if the stools return to a lighter color. See which foods rich in iron to avoid.

2. Consumption of red or black foods

In addition to foods rich in iron, those that have a very intense red color or that have a black color can also change the color of stools, making them darker. Some examples of foods include:

  • Liquorice;
  • Blueberries;
  • Dark chocolate;
  • Gelatin with red dye;
  • Beetroot.

If you suspect that this may be the cause, it is recommended to pay attention to food for 2 or 3 days, avoiding this type of food, and observe if the stools end up clearing. If the stools are still very dark, it is possible that there is another cause and it is important to consult a gastroenterologist.

3. Use of supplements and medications

The use of some supplements, especially iron and lead, as well as the use of some medicines, such as anticoagulants or anti-inflammatories, can lead to dark stools about 1 to 2 days after starting treatment.

What to do: if the change in stool color appears shortly after starting treatment with a drug or supplement, it is recommended to consult the doctor who prescribed it to change the remedy, if possible.

4. Stomach ulcers

Stomach ulcer, also known as gastric ulcer, is a wound that can form on the stomach mucosa and lead to the appearance of some symptoms, such as stomach pain, nausea, vomiting and stomach bleeding, which is noticed through the feces, which become darker and have a stronger smell.

What to do: It is important that the gastroenterologist is consulted in order to identify the cause of the ulcers and, thus, initiate the most appropriate treatment, which may involve the use of medication to decrease and/or neutralize stomach acid, which helps relieve symptoms. Check out more details of treatment for gastric ulcers.

5. Esophageal varices

Esophageal varices occur when blood vessels in the esophagus become dilated, which is usually a consequence of liver changes, and can lead to symptoms when they rupture, resulting in vomiting blood and blood in the stool, which make them dark. In addition, it is possible to notice paleness, dizziness and more wheezing, for example. Know how to recognize the symptoms of esophageal varices.

What to do: in cases where bleeding is very intense and the person loses consciousness, it is recommended that SAMU is activated. In addition, if you have already been diagnosed with esophageal varices, the doctor may recommend the use of some medications according to the severity of the varices and the cause, and surgery may also be indicated in some cases.

6. Cancer of the stomach or intestine

Cancer in the stomach or intestine can also make the stools darker due to the greater sensitivity of this region, with a greater risk of bleeding, which is observed in the stools.

What to do: in this case it is important to follow the treatment indicated by the doctor, which aims to reduce the rate of multiplication of cancer cells and promote their elimination, which may involve performing chemo and/or radiotherapy and surgery sessions.

What makes baby black stools

Dark stools in the baby are normal when they happen right after birth, being called meconium. Meconium is a dark green substance produced by the fetus during pregnancy, which is expelled in the first hours of life. Up to the sixth day of life, stools in a brown or very dark green color may be normal. See other causes of green stool.

However, over a few weeks and months, stools change color and texture, especially after the introduction of new foods, such as porridge, fruits, vegetables, meats and eggs, for example.

In some cases, in babies, a small amount of blood may appear in the stool, making it darker, but it is usually not serious, as they are caused by flu or milk allergy.However, if this occurs, it is important to inform the pediatrician so that the cause can be identified and treatment started.

Understand better why baby stools can turn dark.

When to go to the doctor

Whenever there is a suspicion that dark stools are being caused by the presence of digested blood, it is very important to consult a gastroenterologist. However, it is also important to consult a doctor if there are signs and symptoms such as:

  • Presence of a fetid smell;
  • Intense abdominal pain;
  • Nausea and vomiting;
  • Presence of bright red blood in stool or vomit;
  • Weight loss;
  • Appetite changes.

In these cases, it is normal that, in addition to evaluating the person's symptoms and clinical history, the doctor also asks for some tests to be performed, especially stool examination and endoscopy.

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