THE cause of mucus discolouration (black or grey) includes food colour, fungal infection in the mouth, blood or other infections.
Dear Doctor, When I drink tea, I spit out blackish mucus. Help Anonymous
Dear Anonymous THE cause of mucus discolouration (black or grey) includes food colour, fungal infection in the mouth, blood or other infections. Do you also have a foul smell in your mouth? See a medical personnel for more information and remember to brush your teeth regularly.