Healthy stool is normally brown in color. It is initially green and then turns bright yellowish as it passed across the digestive tract. Later, due to the action of bile, bacteria, bilirubin, protein, fat, water, broken down RBCs, and cellulose and other indigestible plant matter, etc., on stool, it becomes brown in color.

Black dots in stool may not be serious if it occurs irregularly. Black dots in stool on a regular basis may be caused due to simple causes such as intake of certain foods and medications, etc., or due to severe underlying conditions like cancer. Listed below are some of the causes of black dots in stool.

Causes of black dots in stool

Black dots in stool may be cause due to the following reasons:

• The diet: Eating certain kinds of foods can cause black dots in feces, albeit for a temporary period. It can occur due to intake of black licorice, blueberries, bananas, black pepper, black pudding or foods with excessive animal blood, red wine, paprika-laden foods, and undercooked or raw red meat, as well as eating increased amounts of beet or other such iron-rich foods. Undigested fruit seeds may also be eliminated from the body as black dots in stools. Eating excessive amounts of fiber-abundant foods can cause the stool to rapidly pass across the digestive tract and cause loose stools with darkened undigested food particles.
• Medications: Medicines containing lead or bismuth, iron supplements, Pepto-Bismol and other drugs with bismuth subsalicylate, charcoal, vanadium used by body builders, and NSAIDs, naproxen, ibuprofen, or aspirin or other such medications which may trigger stomach bleeding may cause tarred stools on a temporary basis.
• Diarrhea: It refers to increased passage of extremely watery feces. Severe cases of diarrhea, especially those caused due to underlying intestinal parasitic infections or gastrointestinal conditions, may be marked with black dots in stool. Patients may also experience increased irritability, weakness, dehydration, and nausea.
• Digestive tract bleeding: Any kind of bleeding in the stomach, upper small intestine, duodenum, or other sections of the digestive tract can cause stools with black dots along with a foul smell. This is due to hemoglobin oxidation and other chemical actions experienced by such blood in the tract before it gets eliminated from the body. Hemorrhoids, diverticulitis, gastritis, liver cirrhosis associated esophageal varices, severe celiac disease, tuberculosis, gut hemophilia, and Mallory-Weiss tear, etc. are some of the common causes of such bleeding.
• Parasitic infections in the intestine: Intake of drinks, foods, or beverages contaminated with parasites like Giardia lamblia or Entamoeba histolytica can cause intestinal conditions like giardiasis and amoebiasis, respectively. In addition to black dots in stool, patients may also suffer from symptoms like fever, nausea, abdominal cramping, appetite loss, bloody diarrhea, and pain in stomach.
• Cancer: Tumors present in the intestine or the abdomen may sometimes bleed, which can then lead to black spots in stool. Such tumors can also cause tract blockages which in turn may prevent bilirubin from acting on feces, thereby resulting in clay-like grey bowel movements.
• Inflammatory gastrointestinal conditions: A few conditions which may cause black dots in stool are:
  • Ulcerative colitis is marked by inflammation of the colon wall or lining. Its causes are not known, but patients may suffer from bloody stools, abdominal pain, diarrhea, appetite loss, irritability, fatigue, and black dots in stool, etc.
  • Inflammatory Bowel Syndrome or IBS is marked by inflammation of the intestinal wall or lining. In addition to excretion of stools with black dots, patients may also elicit symptoms such as intense abdominal cramping, intestinal wall irritation, and nausea, etc.
  • Crohn’s disease often causes green stools, but it may also sometimes cause black tarry stools.
• Bacterial infections of the intestine: The digestive tract is vulnerable to infections by varied types of bacteria. It often suffers from infection due to intake of contaminated foods and beverages. Cholera is one such condition which occurs due to intake of contaminated water and causes irregular stool along with other intestinal issues such as abdominal cramps, appetite loss, diarrhea, nausea, irritability, and depression, etc. SIBO or small intestinal bacterial overgrowth is marked by infection by clusters of bacteria which causes eliminated of pepper-sized black dots in stool. In most cases, the dark nature of feces is due to the effect of toxins which the body produces when trying to fight and get rid of the infection.
• Ulcers: It is an open wound that forms inside the digestive tract and may cause internal bleeding, which in turn may eventually lead to elimination of such blood along with stool as black dots. Mostly, such bleeding ulcers need to be present in the stomach or other areas of the upper digestive system to be able to cause black dots in stool.
• Other causes: Wounds within the digestive tract caused due to direct trauma, puncture, injuries, or surgery can also cause bleeding and black dots in stool. Abnormal stools may also occur as a side effect of medications or as part of an allergic reaction.

Treatment of black dots in stool

Temporary cases of black dots in stool do not require medical attention. However, prolonged instances need to be checked by a doctor.

Treatment is dependent on diagnosis of the underlying condition that is causing black dots in stool.