A black tongue in the morning is a common symptom of black hairy tongue, a harmless condition resulting from the buildup of dead skin cells on the tongue's papillae, explains Mayo Clinic. Less common causes include fungal infections, viral infections and inflammation of the tongue lining.
Additional symptoms may include an altered taste in the mouth, bad breath, a furry appearance of the tongue and a tickling or gagging sensation, according to Mayo Clinic. Common causes of black hairy tongue include poor oral hygiene, tobacco use, dry mouth, use of medications containing bismuth and irritation from drinking hot beverages. It may also occur after taking antibiotics or while eating a soft diet that does not include enough abrasive foods to rub dead skin cells from the papillae. Extensive use of mouthwashes with oxidizing agents or astringent agents are known to contribute to black hairy tongue.
Black hairy tongue generally requires no medication with most cases resolving on their own, but individuals can choose to treat the issue by brushing their teeth at least twice a day, eliminating contributing factors and gently brushing the tongue with a soft-bristled toothbrush or tongue scraper, notes Mayo Clinic. Flossing daily, using fluoride toothpaste and getting professional teeth cleanings are also recommended.