The initial symptoms of kernicterus are lethargy, decreased muscle tone, and weakness of sucking in the child. Kernicterus, also known as bilirubin encephalopathy, is caused by high levels of unconjugated bilirubin in the blood and is common in newborns. In the early stage of kernicterus, the patient may have mental symptoms such as lethargy and decreased responsiveness, so the early stage of kernicterus is also known as the warning stage. If jaundice is not treated in the early stages, it can worsen gradually and even leave serious sequelae leading to neurological damage. Phototherapy and blood exchange are mainly used to reduce blood bilirubin concentration and treat nuclear jaundice. It is recommended that patients should seek medical treatment as soon as possible after the occurrence of kernicterus, and should not use medication on their own to prevent the development of the disease from causing irreversible damage.