A red or strawberry tongue is caused by a vitamin deficiency, geographic tongue and Kawasaki syndrome, according to WebMD. Scarlet fever also causes a strawberry or red tongue.
A person who is deficient in folic acid or vitamin B-12 can present with a red tongue, as can a person with geographic tongue, says WebMD. Geographic tongue is a benign condition where the tongue has patches of red with white borders that make them look like areas on a map. The patches migrate over the tongue. If this persists for more than two weeks, the patient should consult a doctor to make sure it's not a more serious condition.
Kawasaki syndrome is a childhood disease that affects the blood vessels, says WebMD. It may even affect the arteries in the heart, according to Mayo Clinic. The child has a very red tongue and eyes, a high fever that lasts for days, and swollen hands, feet and lymph nodes. His skin may peel, and he may suffer vomiting and diarrhea during the later stages of the disease. Though the symptoms are frightening, the child usually recovers with no lasting effects.
Scarlet fever is caused by a bacterial infection, says MedlinePlus. Not only is the tongue red, but there is redness in the creases in the groin, and the red rash gives the disease its name.