Jaundice 18mg/dL need to take a blue light, is a newborn hyperbilirubinemia need to be treated, usually need to take a 3~6 days, but the specific how long can’t be generalized, mainly depends on the bilirubin level in the child’s body, usually need to take a blue light until the bilirubin level drops to 12.9mg/dL or less, then you can stop using the blue light. The higher bilirubin level in newborns is related to the short life span of newborns’ erythrocytes and the insufficient uptake and conversion of bilirubin by hepatocytes. In addition, factors such as hemolysis, infection, hypoxia, and prematurity can all lead to an increase in the level of bilirubin in newborns, and the above factors can lead to the continuous production of bilirubin in the body of newborns, so the duration of the blue-light treatment cannot be generalized. Generally speaking, the total bilirubin level of newborns reaches 12.9mg/dL, and then blue light treatment is needed. Generally speaking, the bilirubin level can be lowered by 4~5mg/dL per day after blue light irradiation, but as the bilirubin in newborns’ bodies is still being produced, it may take 3~6 days or even longer. If the examination finds that the newborn’s jaundice is 18mg/dL, please consult the doctor promptly and follow the doctor’s instructions for treatment.