Dark circles under the eyes is a common condition that is not serious and appears more often as people age. There are 2 major reasons that the area under the eyes can look dark. First, it can appear dark because of puffy lids that cast a dark shadow on the skin. Second, the skin itself is actually darker in color.
The skin around the eyes is very delicate and thin. Underneath the skin there is a collagen matrix that is like the scaffolding of the skin. Over time the collagen can break down and the skin slowly loses its shape and form. We can not see the change in the beginning but over time we will see it as baggy or wrinkled skin.
Loose skin can fill with fluid very easily and since the skin around the eyes is already naturally thin, eyelids can stretch and fill up with fluid quite often. This is what happens with puffy eyelids. This puffiness then casts a shadow underneath and then it appears as a dark circle under the eye. So, you can decrease the dark shadow by decreasing the fluid retention in the eyelid area by sleeping well, sleeping with your head elevated, applying cool compresses, avoiding smoking, and limiting salt.
There is less that can be done when the skin actually changes color. When the skin gets thinner, the reddish-blue blood vessels under skin are more prominent and closer to the surface and their color can be seen more through the thin skin. Darker skin color can also happen because of changes that occur from the sun influence and from genetic influence.
Allergies can magnify and speed up any of these conditions because chronic inflammation from allergies cause fluid retention, pigment deposits, and collagen breakdown. See your eye provider to be sure any allergies are fully treated and check for any other rarer conditions that may cause darkening of the skin.
