The specific timing of the peak of jaundice is related to the cause of jaundice and the degree of the condition, and needs to be analyzed on a case-by-case basis. Jaundice can be physiological or pathological. Physiological jaundice is mostly seen in the neonatal period, and is a temporary jaundice caused solely by the metabolic characteristics of bilirubin, which is a normal phenomenon and usually appears 2-3 days after birth, reaching a peak in 4-6 days. In contrast, pathological jaundice in newborns often appears within 24 hours after birth, and some of them may appear within 1 week to several weeks after birth, and the degree of jaundice is heavy, fast progressing, and long lasting, and it can reappear after it subsides. Because of individual differences in the time of appearance of pathological jaundice, it is not possible to determine the exact time of its peak. In addition, jaundice is not unique to newborns, but can also occur in adults, such as in the case of jaundice hepatitis, whose peak is usually within 1-3 weeks. In the case of jaundice, such as scleral yellowing, peripheral skin yellowing, and yellow urine, prompt consultation with a pediatrician is recommended for newborns and with a hepatologist for adults to identify the cause and provide targeted treatment.