Cancer cells divide more quickly than healthy cells, and chemotherapy drugs effectively target those cells. Unfortunately, fast-growing cells that are healthy can be damaged too. There are many different chemotherapy drugs with the potential for many different side effects.
Symptoms & Signs. Dark circles under the eyes are a common complaint of both men and women, although they can occasionally be seen in children. As people age, the skin becomes thinner and collagen is lost, sometimes enhancing the appearance of blood vessels beneath the eyes and making the area appear darker.
Heredity Edit. In most cases, the dark circles under the eyes are blood vessels that can be seen through the skin. The skin around the eyelids (periorbital skin) is the thinnest skin in the body (around 0.5 mm thick compared with 2mm in other areas). Like varicose veins, dark circles under the eyes are usually an inherited trait.