Can quadruple therapy for Helicobacter pylori cause black stool?

The quadruple therapy for Helicobacter pylori may cause black stool, usually related to the bismuth component in the medication. The quadruple therapy includes proton pump inhibitors, two antibiotics, and bismuth agents, among which bismuth agents combine with sulfides in the intestine to form black bismuth sulfide, which is a normal phenomenon. When using bismuth agents containing potassium bismuth citrate or colloidal bismuth pectin, the color of stool may appear dark brown or black, but there is no special odor and the bowel movement pattern remains unchanged. This phenomenon will gradually disappear within 2-3 days after stopping the medication, and during this period, increasing water intake appropriately can help with metabolism. Some patients may experience mild diarrhea due to antibiotic use, but it will not directly affect the color change of stool. If black stool is accompanied by symptoms such as tar like appearance, fishy smell, dizziness, palpitations, etc., be alert to the possibility of gastrointestinal bleeding. Individuals who have been taking nonsteroidal anti-inflammatory drugs for a long time or have a history of gastric ulcers should pay more attention to differentiation. The key to distinguishing stool discoloration and bleeding caused by bismuth agents is that the former has a uniform color without mucus, while the latter often contains blood clots and a positive hemoglobin test.

During treatment, it is recommended to maintain a light diet and avoid alcohol and spicy foods that can increase gastrointestinal burden. Regularly review the carbon-13/14 breath test to evaluate the efficacy, and make a comprehensive judgment based on other symptoms when observing changes in stool characteristics. If there is persistent black stool or worsening abdominal pain, timely follow-up should be sought, and if necessary, fecal occult blood or gastroscopy examination should be performed.