hi Heredity,Age , fatigue ,Allergies, asthma, and eczema,Anaemia,pregnancy and menstruation , liver problem may lead to darl circles or hyperpigmentation . treatment is based on the cause , cause is to be corrected along with skin whitening creams which is totally decided on type of skin and extent of condition.CONSULT DERMATOLOGIST TO LOOK FOR THE EXTENT OF SCARING , AS SUPERFICIAL ONES CAN BE  REDUCED WITH CREAMS AND FEW DEEPER ONES MAY NEED CHEMICAL PEELING OR LASER THERAPY .