According to the Merck Manual, if your tongue discoloration is not due to something that stained it, it can be due to injury, poor oral health, disease, or other conditions. One common condition is oral hyperpigmentation, which can cause blue, purple, brown, black, or grey spots in the mouth, according to The Journal of Pharmacy and BioAllied Sciences. Specifically, hyperpigmented spots on the tongue can be a sign of the rare adrenal disorder Addison’s Disease or the rare genetic disorder Peutz-Jeghers Syndrome. Skin pigmentation changes can also be a result of chemotherapy, according to the National Cancer Institute. While this is common and temporary with chemotherapy and treatable at home, patients should note any changes to the tongue and skin and tell their medical provider.
Black dots on the tongue could also appear due to a harmless condition called black hairy tongue. According to The Mayo Clinic, this condition happens when a buildup of dead skin cells on the papillae on the surface of the tongue don’t shed normally. The result is a tongue that has a black “furry” appearance. Other symptoms of black hairy tongue include a metallic taste in the mouth, bad breath, or a tickling sensation. Though there are many causes for a black hairy tongue, some common ones are bacteria growth due to antibiotics, poor oral hygiene, tobacco use, excessive coffee and alcohol consumption, and a soft food diet. Luckily, this condition should go away with good oral hygiene practice. According to Medline Plus, you can potentially treat it with antifungal medication.