Dark blue veins beneath the tongue are a common sight, often prompting questions about their cause. This appearance is typically a normal anatomical feature, not a sign of a health problem. This article explains why these veins appear blue and when their appearance might warrant medical attention.
Understanding the Blue Appearance of Veins
The veins visible under the tongue are known as sublingual veins, including the deep lingual veins or ranine veins. Located on the underside of the tongue, they drain its ventral surface and the sublingual glands, eventually joining the internal jugular vein.
The dark blue appearance of these veins is an optical illusion; blood within them is not blue. Blood, whether oxygenated or deoxygenated, is always red. Oxygenated blood in arteries is bright red, while deoxygenated blood in veins is a darker red or maroon.
The perception of blue veins occurs due to how light interacts with the skin and blood vessels. White light penetrates the skin. Red light, with its longer wavelength, travels deeper and is absorbed by hemoglobin. Blue light, with its shorter wavelength, does not penetrate as deeply and is mostly reflected and scattered back to the eye.
This scattering effect makes blue light more visible, creating the illusion that veins appear blue or purplish. The thin skin under the tongue makes sublingual veins more visible than veins elsewhere, where thicker skin might obscure this effect. This is a normal phenomenon, a trick of light and human perception.
When to Be Concerned About Sublingual Veins
While dark blue veins under the tongue are generally a normal anatomical finding, their prominence can vary and often increases with age. Sublingual varices, which are dilated and tortuous veins, become more common with aging. Slight differences in their size or color are common and typically not a cause for concern.
However, certain changes or accompanying symptoms may indicate a need for medical evaluation. These include sudden swelling, persistent pain, or tenderness in the area. Unexplained bleeding from the veins or new lumps or masses under the tongue also require professional assessment.
A sudden change in vein color, such as becoming black, unusually pale, or white, warrants medical attention. The appearance of ulceration, an open sore, on or around the veins, also requires prompt examination. While dark blue veins under the tongue are a common and expected feature, awareness of unusual changes ensures timely medical assessment.