Jaundice into the brain, i.e. neonatal bilirubin encephalopathy, is more critical and is preceded by lethargy, weakened sucking reflexes, depression, and decreased muscle tone. If the bilirubin level is particularly high in the neonatal period, it may cross the blood-brain barrier and damage the basal nucleus, basal ganglia and other parts of the body, leading to a series of clinical symptoms. The precursor, also called the warning period, is characterized by symptoms such as lethargy, weakened sucking reflex, depression, and hypotonia, occasionally accompanied by screaming and vomiting. Neonatal bilirubin encephalopathy is characterized by convulsions, seizures, and a severe reduction in muscle tone. Recovery from the disease may be characterized by a reduction in convulsions and a decrease in muscle tone, but may result in sequelae such as cerebral palsy and damage to the motor nerves of the child. Jaundice should be strictly monitored in the neonatal period, and if jaundice is abnormal, prompt medical attention should be sought to avoid jaundice into the brain.