When to call

Call an ambulance or go to the emergency department now if your baby has jaundice and

Is less than 24 hours old.
Is sleepier than normal or difficult to wake.
Is not feeding.
Is floppy or stiff, or has jerking or twitching movements.
Has a temperature of 38C (100.4F) or more, or 36C (96.8F) or less, feels hot or cold to the touch, or is shivering.
Has not been producing any wet nappies.
Has difficulty breathing — grunting noises, the stomach sucking in under the ribcage, breathlessness or very fast breathing.

Source: NHS, Jaundice in babies

Ask for an urgent GP or midwife appointment, or ring your out-of-hours line, if your baby is over 24 hours old and:

You think they have jaundice.
They have been diagnosed with jaundice and it is not getting better, or is getting worse.
Their pee is dark yellow or brown, or their poo is a pale creamy colour. The NHS advises keeping a sample of the poo to show a midwife or doctor.
The jaundice has lasted longer than 14 days (HSE).

The AAP adds its own list: call if your baby's skin turns more yellow, if the abdomen, arms or legs are yellow, if the whites of the eyes are yellow, or if your baby "is hard to wake, fussy, or not nursing or taking formula well."

Why the first 24 hours are different

This is the single most important thing on this page. Ordinary newborn jaundice does not appear on day one.

NICE's guideline on neonatal jaundice (CG98) treats jaundice in the first 24 hours as a different clinical situation entirely. Its recommendations are specific:

"In all babies with suspected or obvious jaundice in the first 24 hours of life, measure and record the serum bilirubin level urgently (within 2 hours)."
Then continue measuring "every 6 hours until the level is both below the treatment threshold and stable and/or falling."
Arrange "an urgent medical review... as soon as possible and within 6 hours for babies with suspected or obvious jaundice in the first 24 hours of life to exclude pathological causes of jaundice."

The AAP says the same in plainer language: "Any baby that has jaundice in the first 24 hours after birth should have the bilirubin level measured right away."

For babies over 24 hours old with obvious or suspected jaundice, NICE still says to measure the bilirubin level urgently — within 6 hours.

What ordinary jaundice looks like

The NHS describes the yellow appearing "in the whites of their eyes", "on their skin – this usually starts on the face and head and can spread to the rest of the body", and "under their tongue or inside their cheeks."

Timing, from the NHS: "For most babies with jaundice, the yellow is most noticeable when they're around 3 days old. It usually takes around 2 weeks for the jaundice to go." The HSE puts the onset at 2 to 3 days old and says symptoms last between 10 and 14 days.

The AAP notes a difference by feeding method that saves a lot of unnecessary worry: "In breastfed babies, it is common for jaundice to last 1 month or occasionally longer. In formula-fed babies, most jaundice goes away by 2 weeks." Its threshold for a call is jaundice lasting more than 2 weeks in a formula-fed baby, or longer than 4 weeks in a primarily breastfed one.

How to look for it

NICE gives specific instructions, and they matter because visual assessment is unreliable:

"Check the naked baby in bright and preferably natural light."
"Examine the sclerae and gums, and press lightly on the skin to check for signs of jaundice in 'blanched' skin."
"Be aware that changes to skin pigmentation because of hyperbilirubinaemia may be harder to see in darker skin."
And critically: "Do not rely on visual inspection alone to estimate the bilirubin level in a baby with suspected jaundice."

The NHS's practical version: the yellow is easier to see in bright light or sunlight, and pressing gently on the tip of your baby's nose or forehead may make it easier to see. It states plainly that "it can be harder to see yellow on black or brown skin", and the HSE adds that yellowing "may be more obvious in their eyes."

Why it happens

Jaundice is caused by a build-up of bilirubin, a waste product from the breakdown of red blood cells that is normally removed by the liver. The NHS explains that a newborn's liver "is not able to work properly immediately", so bilirubin accumulates; after a few weeks the liver develops fully and levels return to normal.

NICE identifies four factors that make significant jaundice more likely: gestational age under 38 weeks; a previous sibling with neonatal jaundice requiring phototherapy; the mother's intention to breastfeed exclusively; and visible jaundice in the first 24 hours of life. Babies with any of these should get an additional visual inspection by a healthcare professional during the first 48 hours.

Less commonly, jaundice signals something else: infection, incompatible blood groups between mother and baby (haemolytic disease), abnormalities in the baby's blood cells, Gilbert's syndrome, or a liver problem. The NHS is clear that "in most babies, jaundice is not a sign of another health condition."

What actually helps

Feeding is the intervention. The NHS: "Encouraging your baby to feed regularly, around 8 to 12 times a day, can help them get better more quickly. If they're sleepy, try waking them for feeds." The HSE says to feed at least every 3 to 4 hours, wake for feeds, and check your baby has a wet nappy before each feed. NICE tells clinicians to "encourage mothers of breastfed babies with jaundice to breastfeed frequently, and to wake the baby for feeds if necessary", and to provide lactation support.

Phototherapy is the treatment. A special light on the skin, usually in hospital. The NHS says most babies need around 48 hours of it; the HSE says a hospital stay of at least 12 to 24 hours. Rarely, a baby needs intravenous immunoglobulin or an exchange transfusion — NICE covers both.

What does not help, and is dangerous: the AAP states directly that "putting your baby into sunlight is not a safe way to treat jaundice." It is a persistent piece of advice online and it should be ignored.

One more AAP warning that rarely appears elsewhere: tell your baby's doctor if you eat fava beans (broad beans), or use mothballs, henna or herbal remedies, because in rare cases these can cause severe jaundice.

Jaundice that will not go away

NICE defines prolonged jaundice as lasting more than 14 days in a baby born at 37 weeks or more, or more than 21 days in a baby born before 37 weeks. At that point the guideline says to look for pale chalky stools and dark urine staining the nappy, measure the conjugated bilirubin, do a full blood count and blood group with a Coombs' test, consider a urine culture if a urinary tract infection is suspected, and check that routine metabolic screening has been done.

The reason for the stool and urine question is specific: a conjugated bilirubin level above 25 micromol/litre "may indicate serious liver disease", and NICE says to follow expert advice in that case. This is why every source tells you to look at the nappy — pale, chalky poo and dark urine in a jaundiced baby is the finding that changes the diagnosis.

What to let go of

Jaundice is not caused by anything you did, and the NHS's own framing — "usually harmless and gets better without treatment" — is accurate for the great majority of babies. What it is not is something to watch and wait on in the first day of life, or in a baby who is deeply yellow, sleepy or feeding poorly. Those are the two situations where speed matters.

Newborn Jaundice