Finding an unexpected black spot inside your mouth can be unsettling, whether it appears on your gums, the roof of your palate, or the inside of your cheek. It is important to know that the vast majority of black spots are benign and stem from common, non-serious causes. Understanding the source of the discoloration is the first step in determining whether the spot is harmless or requires a professional evaluation. Discoloration occurs when foreign materials are deposited in the oral tissues or when the body produces excess pigment in a localized area.
Temporary Spots from Injury or Diet
Many dark spots result from minor, localized trauma, often leading to a blood blister or oral hematoma. This occurs when small blood vessels beneath the mouth lining rupture, trapping blood in the tissue layers. Accidental cheek biting, sharp food edges, or a burn from a hot drink can easily cause this localized bleeding.
The resulting spot appears dark red, purple, or black because the trapped blood clots and darkens over time. A blood blister typically resolves on its own within a week or two as the body naturally reabsorbs the blood. Temporary staining from consuming dark-colored foods and beverages, such as berries, coffee, or red wine, is another common cause. This surface-level staining fades quickly with normal brushing and saliva flow.
Pigment Changes and Amalgam Tattoos
Some dark spots are permanent but harmless, representing a concentration of pigment or foreign material in the tissue. The oral melanotic macule is the most common melanocytic spot, appearing as a flat, uniformly colored brown or black dot, similar to a freckle. This macule results from a localized overproduction of melanin pigment by the cells.
A frequent cause of a stable dark spot is an amalgam tattoo, a specific form of exogenous pigmentation. This gray, blue-black, or black discoloration occurs when particles from a silver-mercury dental filling become permanently embedded in the gum or cheek tissue during a dental procedure. The metallic material is inert, meaning the spot will not fade or change color over time. Oral nevi, or moles, are also possible, appearing as a slightly raised or flat spot composed of a benign cluster of pigment cells.
Systemic Conditions and Medication Effects
Black spots or diffuse discoloration can sometimes manifest a change occurring throughout the body, not just in the mouth. Certain endocrine disorders, such as Addison’s disease, cause a widespread increase in pigmentation across the skin and mucous membranes. This occurs because adrenal gland dysfunction leads to the overproduction of a hormone that stimulates melanin-producing cells.
This systemic pigmentation often presents as multiple, patchy areas or a general darkening of the cheeks, lips, or gums, unlike localized dots. A variety of medications can also cause oral pigmentation as a side effect, including certain antimalarials, specific antibiotics like minocycline, and some chemotherapy agents. These drugs either stimulate melanin production or cause the drug compounds or their metabolites to deposit directly into the oral tissues.
Features Requiring Immediate Medical Attention
While the majority of black spots are benign, any pigmented lesion that changes or exhibits concerning features should be evaluated immediately by a dentist or oral surgeon. The most serious possibility is oral melanoma, which can be identified using an adaptation of the ABCDE criteria used for skin lesions.
ABCDE Warning Signs
Pay close attention to the following features:
- Asymmetry: One half of the spot does not match the other.
- Border irregularities: The edges are ragged, notched, or blurred.
- Color variation: The spot shows multiple shades of brown, black, blue, or red.
- Diameter: The spot is larger than six millimeters, or about the size of a pencil eraser.
- Evolution: Any rapid change in the size, shape, color, or elevation of the spot, or the development of new symptoms like bleeding or pain, warrants an urgent professional consultation.