i) When there is an abnormal rise in the bilirubin level which may be due to physiological or pathological jaundice or any other problem.
ii) Prophylactic phototherapy is indicated in special circumstances i.e. tiny infants who are likely to develop dangerous levels of bilirubin and in severely bruised premature infants. In hemolytic disease of the newborn, phototherapy is used while the rise in the serum bilirubin level is plotted and while waiting for exchange transfusion. In such cases, phototherapy is started immediately at birth.