Colloidal bismuth pectin is a kind of western medicine, which is commonly used in capsules, granules and suspensions. It is a gastric mucosal protective drug. Colloidal bismuth pectin can be used to treat peptic ulcer and chronic superficial gastritis and atrophic gastritis.

Because colloidal bismuth pectin contains bismuth agent, when the drug interacts with inflammation and ulcer surface in gastrointestinal tract, it will cause the color of stool to change, which will cause patients to have black stool, which will lead to patients having black stool after eating colloidal bismuth pectin.

It is usually a normal physiological phenomenon. After stopping using the drug 1-2 days, the color of stool can become normal.