My son who Robert is 32 yrs old called me yeaterday and told me he woke up with a black tongue. He did not eat anything the day before that would have stained his tongue! He does smoke. Also, about 2 weeks ago he had a lot of blood in his stool. Please help
Also Pepto Bismol is known to cause a black tongue and/or black stools
I found a number of websites that discussed in detail how Pepto-Bismol can turn a person's tongue black. Apparently, an active ingredient in the medication reacts with sulfur to create the black substance. Something I ate last night had sulfate in it, so the reaction happened in my mouth while I was sleeping."