The generic name of Rezudel is Bismuth Potassium Citrate Tablet, it is normal to pass black stool after taking Bismuth Potassium Citrate. Bismuth potassium citrate belongs to gastric mucous membrane protector, can play the role of protection and astringency of gastric mucous membrane, can be used for the treatment of chronic gastritis and relief of excessive stomach acid caused by heartburn, acid reflux, stomach pain and other symptoms. It is contraindicated in people who are allergic to this drug, severe renal insufficiency, pregnant and lactating women. Taking this drug can lead to darkening of feces and production of black stools, so passing black stools after taking bismuth potassium citrate is a normal condition. Adverse reactions to this medication also include loss of appetite, nausea, vomiting, and rash. Patients who need to use bismuth potassium citrate tablets for treatment should use the drug under the guidance of a doctor.