What should you know about bismuth subsalicylate black stool?

The bismuth in this medicine can combine with substances in the gut and produce a dark stool or tongue. The change is usually temporary and is different from blood loss, although appearance can be difficult to judge at home. Digestive bleeding may produce black, sticky, tar-like stool and can occur with gastritis, Helicobacter pylori infection, or a peptic ulcer. Bismuth subsalicylate also contains a salicylate, so it may not be suitable for everyone, including some people with salicylate allergy or bleeding concerns.

Check the product label and record when you started it, how often you take it, and when the stool changed. Do not exceed the label directions or combine it with another salicylate-containing product without advice. If you take blood-thinning medicine, have an ulcer history, or have a bleeding disorder, ask a pharmacist or clinician before further doses. Contact a clinician if the stool remains black after stopping or the cause is uncertain.

Go to urgent care for black tarry stool with fainting, dizziness, marked weakness, rapid heartbeat, vomiting blood, severe abdominal pain, or pale clammy skin. Seek prompt advice for repeated black stools or ringing in the ears, confusion, or unusual breathing after taking too much. Take the packaging with you if possible.

Is this likely to be a medicine colour change? Is bismuth subsalicylate appropriate with my other medicines and health conditions? Do I need testing for bleeding, gastritis, or an ulcer?