What are some common causes that would make human feces come out almost black and happens every couple weeks to a month?

1. Blood in the stool (melena)

*Dark, black stools can indicate the presence of blood in the stool. This is usually caused by bleeding in the upper gastrointestinal tract, such as the stomach or small intestine.

*Common causes of upper GI bleeding include:

* Peptic ulcers

* Gastritis

* Esophagitis

* Variceal bleeding

* Mallory-Weiss tears

2. Medications

*Certain medications can cause the stools to turn black or dark brown, including:

* Iron supplements

* Pepto-Bismol

* Activated charcoal

* Antacids containing bismuth

3. Foods

*Some foods can also darken the stools, such as:

* Black licorice

* Blueberries

* Cherries

* Grapes

* Red wine

4. GI conditions

*Certain GI conditions can cause the stools to turn black or dark brown, including:

* Crohn's disease

* Ulcerative colitis

* Pseudomembranous colitis

* Diverticular disease

5. Other causes

*Rarely, black or dark brown stools can be caused by other conditions, such as:

* Melanoma

* Whipple's disease

* Addison's disease

If you are experiencing black stools and you are not sure what is causing them, it is important to see your doctor for evaluation. This is especially important if you have any other symptoms, such as abdominal pain, nausea, vomiting, or weight loss.