Spots on the tongue that resemble skin freckles are known medically as oral melanotic macules. These flat, brownish spots are overwhelmingly benign, meaning they are harmless and not a sign of disease. They represent a localized increase in pigment production and are generally stable and require no treatment.
Defining the Spots on the Tongue
Oral melanotic macules (OMMs) are non-cancerous lesions resulting from an overproduction of melanin pigment. Melanin is the same substance responsible for hair, eye, and skin color, produced by specialized cells called melanocytes. Unlike skin freckles, which are often called ephelides and darken with sun exposure, OMMs are not caused by ultraviolet light.
These macules typically appear as flat, well-defined patches ranging in color from light brown to black. They are usually small, often less than 7 millimeters in diameter, and tend to remain stable in size and shape over time. While they can appear anywhere in the mouth, including the gums, inner cheek, and lips, they are also found on the tongue.
The underlying cause is the accumulation of melanin within the tissues of the oral lining. OMMs are far more common than other pigmented lesions in the mouth, accounting for a large percentage of all oral lesions that involve melanin. OMMs are generally solitary, but multiple macules may rarely indicate a more widespread condition like Peutz-Jeghers syndrome or Addison disease, requiring further testing.
Other Benign Causes of Tongue Discoloration
Spots or discoloration on the tongue not related to melanin pigment often result from trauma. This includes accidentally biting the tongue or scalding it with hot food or drinks, which leaves a temporary red or dark sore. These spots are usually painful and resolve naturally once the injury heals.
Temporary staining is another frequent explanation for dark spots. This is often caused by consuming certain foods, coffee, tea, or using tobacco. Medications containing bismuth, such as some stomach remedies, can also cause a temporary black discoloration that resolves after stopping the medicine.
Other conditions alter the tongue’s surface texture, sometimes making it appear patchy or discolored. Geographic tongue (benign migratory glossitis) creates smooth, red, map-like patches surrounded by a slightly elevated yellowish-white border. These patches are caused by a loss of the tiny projections on the tongue’s surface and characteristically change location over days or weeks. Black hairy tongue is another condition where the papillae become elongated, trapping bacteria and debris, resulting in a furry, dark appearance.
When to Consult a Healthcare Professional
Although most spots on the tongue are benign, professional evaluation is necessary if a pigmented area changes in size, shape, or color over a short period. Immediate attention is warranted if the lesion becomes noticeably larger or develops irregular borders.
Evaluation is also necessary if the spot becomes raised, lumpy, or ulcerated, rather than remaining flat like a macule. Consult a doctor if the spot is painful, bleeds without injury, or is associated with difficulty swallowing or speaking. A persistent sore, lump, or red or white patch that does not heal within two weeks requires medical assessment to rule out serious concerns.