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.
Other Causes of Dark Circles. Dark circles under the eyes may be hereditary. Because the skin under the eyes is very thin, when blood passes through the area it can produce a dark color, much like the blue color of your veins. The thinner your skin, the more the circles will be evident. Another cause can be overexposure to the sun. Another much-ignored cause of dark circles is allergies.