What are the causes of black stool / faeces?
Generally, black stool indicates the presence of bleeding somewhere in the gastrointestinal tract. It is a warning sign that something may be wrong. I would keep track of it, and if it happens again soon, call your doctor and have a stool test done to check for blood. It could be something insignificant, or it could be serious. Write down dates and diet (including beverages) when it occurs, to possibly help with diagnosis. If it continues, you will probably have to have a colonoscopy and an endoscopy. These can be done on the same day. Ask for lots of tranqs and versed. The procedures don’t leave you with pain. Most people bounce right back.