My husband has a blacken tongue. Some of it washed off and is now red. Please help. He has not eaten anything for this to happen.

Hi,
When you say "it is now red", is it the normal color of red? Or is it much, much, deeper color red?
Is he allergic to any food or drink? It could be an allergic reaction.
The best thing to do is for him to see a doctor; maybe an Ear-Nose-Throat (ENT) doctor, or even a family MD. Getting a Professional opinion is the only way he will know what happened. It is probably nothing serious, but there is only one way to find out.
I do wish you the best, and Happy New Year.

I found this:

http://archfami.ama-assn.org/cgi/reprint/9/3/219.pdf

Apparently, black taste buds on dark skinned people is common and not of consequence. Hairy tongue seems to be a disease.