Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern.... As per your complain a black spot on tongue can be due to a few reasons like Hyperpigmentation due to excessive submucosal deposition of melanin pigment in that area and at times it can be genetic also.. Other reason can be Black Hairy Tongue which is due to either poor oral hygiene , bacterial or fungal growth over tongue, pigmentation of the dead cells over the tongue caused by the bacterial acids or coloured foods, excess intake of tea and coffee, smoking and alcohol intake.. At times it can also be due to hyperpigmentation caused as a result of some injury to the tongue causing inflammatory hyperpigmentation... In very rare cases it can be due to oral cancer but the chances are very less.. You should consult an Oral Physician and get evaluated and if there is some doubt the physician can take a biopsy to confirm the diagnosis.. You can cut down on tea,coffee,smoking and alcohol and maintain a good oral hygiene.. Do soda bicarb gargles and use a tongue cleaner to clean the tongue.. In case if there seems no improvement proper treatment by an oral physician after a correct diagnosis has to be done.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..