The causes of black tongue and bitterness usually include filiform papillae hyperplasia, hyperkeratosis and increased pigmentation, etc., which need to be treated by doctors as soon as they are detected. Tongue black, bitter mouth is usually due to filiform papillae hyperplasia and hyperkeratosis, as well as increased pigmentation and lead to, generally can be called black hairy tongue, the appearance of the tongue appears hairy, black phenomenon, there will be a metallic taste in the mouth caused by the bitter mouth, at this time should be early to the hospital stomatology department to clarify the cause of the disease, for targeted treatment. Black hairy tongue is a benign disease, also has a certain degree of self-limitation, generally do not need treatment to be able to self-cure, the patient should pay attention to oral hygiene, keep the oral cavity clean, quit smoking and alcohol.