Untreated jaundice in babies can cause brain damage, but this happens only when bilirubin levels become very high and stay high without proper treatment.[1][2][4] Jaundice itself is very common and usually harmless, yet in rare severe cases it can lead to a type of brain injury called kernicterus.[1][3][4][5]
What jaundice is and why it happens
Jaundice is the yellow coloring of a baby’s skin and eyes that appears when there is too much bilirubin in the blood.[1][3][4] Bilirubin is a yellow pigment that forms when the body breaks down old red blood cells.[1][4]
In newborns, the liver is still maturing, so it may not remove bilirubin quickly enough.[4] As a result, about half of full term babies and up to 80 percent of preterm babies develop some degree of jaundice in the first week of life.[1][4] In most babies this is mild, appears a few days after birth, and goes away on its own or with simple treatment like phototherapy lights.[1][3][4]
How jaundice can lead to brain damage
The danger appears when bilirubin rises to very high levels and is not treated. Bilirubin can then cross the baby’s still‑developing blood brain barrier and enter brain tissue.[3][4][6] When this happens, it can damage specific areas of the brain and nervous system.
Doctors use several related terms for this:
• Acute bilirubin encephalopathy
This is the early stage of brain injury from very high bilirubin.[2][4] A baby may become very sleepy, feed poorly, have a high pitched cry, or develop abnormal muscle tone.[2][3][4] If treatment starts at this stage, the damage can often be stopped or greatly reduced.[2][4]
• Kernicterus
If severe jaundice continues or is not treated, acute bilirubin encephalopathy can progress to kernicterus.[1][2][3][4] Kernicterus is permanent, chronic brain damage caused by bilirubin toxicity.[1][4][5] It affects parts of the brain that control movement, hearing, vision, and learning.[1][3][4][6]
According to resources such as Cerebral Palsy Hub and medical reviews on neonatal hyperbilirubinemia, kernicterus can lead to athetoid cerebral palsy, hearing loss, vision problems, learning disabilities, and other lifelong disabilities.[1][3][4][5][6]
Signs that jaundice may be becoming dangerous
Most jaundice does not cause brain damage, but parents and caregivers should watch for warning signs of severe jaundice and bilirubin related brain injury.[1][2][3][4] These may include:
• Yellow color spreading from the face to the chest, belly, arms, and legs
• Very poor feeding or refusal to feed
• Extreme sleepiness, hard to wake, or floppy body
• High pitched or unusual crying
• Arching of the back or neck
• Stiff or very floppy muscles
• Trouble breathing or pauses in breathing
• Seizures or abnormal eye movements[1][2][3][4]
If any of these signs appear in a jaundiced baby, it is an emergency and the baby needs immediate medical care.[2][3][4]
Who is at higher risk
Some babies are more likely to develop severe jaundice that could threaten the brain.[1][2][3][4] Risk factors include:
• Premature birth before 37 or 38 weeks, because the liver is more immature[1][2][3][4]
• Significant bruising or scalp swelling from birth trauma, which causes more red blood cells to break down[1][2][3]
• Blood type incompatibility between mother and baby, such as Rh or ABO problems, which can cause rapid destruction of red blood cells[3][4]
• A previous child who had severe jaundice or needed phototherapy or exchange transfusion[1][3]
• Certain genetic conditions like G6PD deficiency that increase the breakdown of red blood cells[2][4]
• Dehydration or poor feeding, including difficulties with breastfeeding, which can raise bilirubin levels when the baby is not getting enough milk[1][2][4]
Babies with these risk factors need closer monitoring of bilirubin levels and follow up checks after discharge from the hospital.[1][2][3][4]
What kinds of brain damage can occur
When untreated jaundice leads to kernicterus, the brain injury is permanent.[1][4][5] Different areas of the brain may be affected, which explains the range of problems seen. Reported long term effects include:
• Cerebral palsy, especially athetoid type, with involuntary, twisting movements and motor difficulties[1][3][4][5]
• Hearing loss, often severe and permanent, due to damage in the parts of the brain and nerves that handle sound[1][2][3][4][6]
• Problems with vision or unusual eye movements[1][3][4]
• Speech and language delays or difficulties[1][3][4]
• Learning disabilities and cognitive impairment[1][3][4][5]
• Seizures and other neurological problems[1][3][4][6]
• Problems with balance, coordination, and muscle control[1][3][4][6]
Medical reviews on bilirubin induced neurologic dysfunction also note that even milder but prolonged elevations in bilirubin, below the level that causes classic kernicterus, may still be linked with subtle cognitive, motor, or behavioral issues.[4]
Why early checks and treatment matter
The good news is that kernicterus is widely considered preventable when jaundice is recognized and treated quickly.[1][2][3][4][5] Hospitals and clinics now use bilirubin screening, visual checks, and follow up visits to catch rising levels before they harm the brain.[1][2][3][4]
If a baby’s bilirubin level is too high or rising quickly, common treatments include:
• Phototherapy
The baby is placed under special blue lights that help break down bilirubin in the skin into forms the body can remove more easily.[1][3][4]
• Exchange transfusion
In very severe cases, some of the baby’s blood is replaced with donor blood to rapidly reduce bilirubin levels.[1][3][4] This is used when there is a high risk of brain injury and is done in intensive care.
• Treating the cause
Doctors may treat underlying issues such as blood type incompatibility, infections, or dehydration, and ensure that feeding is going well so the baby can clear bilirubin.[2][3][4]
According to clinical and public health literature, when these treatments are given in time, most babies recover fully and do not develop brain injury.[1][2][3][4] Problems usually happen when severe jaundice is missed, treatment is delayed, or follow up after discharg
