The American Academy of Pediatrics says spit-up, also called reflux or gastroesophageal reflux (GER), is the movement of stomach contents into the esophagus and sometimes out through the mouth and nose. MedlinePlus says a small amount of gastroesophageal reflux is normal in young infants. The NHS says reflux usually happens because the ring of muscle inside the baby's oesophagus can be weak, which allows milk to come back up easily.

Baby Reflux: What's Normal and When to Worry

Last updated 2026-07-12

Baby reflux is when a baby brings up milk during or shortly after feeding, according to the NHS. ¹ MedlinePlus says a small amount of this gastroesophageal reflux is normal in young infants. ² The NHS says it usually starts before a baby is 8 weeks old and gets better by the time they are 1. ¹

Key takeaways

The NHS says infant reflux usually starts before a baby is 8 weeks old and gets better by the time they are 1 year old. ¹
The American Academy of Pediatrics says GER usually begins at about 2 to 3 weeks of age, peaks between 4 and 5 months old, and goes away for most full-term babies by 9 to 12 months. ³
MedlinePlus says a small amount of gastroesophageal reflux is normal in young infants. ²
The American Academy of Pediatrics says feeding and position changes are recommended as first-line therapy for both GER and GERD. ³
The NHS says to make sure a baby sleeps flat on their back, that they should not sleep on their side or front, and not to raise the head of their cot or Moses basket. ¹
The NHS says to ask for an urgent GP appointment or call NHS 111 if a baby's vomit is green or yellow or has blood in it, or if the baby is projectile vomiting. ¹

Urgent: baby reflux warning signs

**MedlinePlus says a small amount of gastroesophageal reflux is normal in young infants. ² MedlinePlus adds that ongoing reflux with frequent vomiting can irritate the esophagus and make an infant fussy. ² The NHS says to ask for an urgent GP appointment or call NHS 111 if a baby has vomit that is green or yellow or has blood in it, is projectile vomiting, has blood in their poo, has a swollen or tender tummy, has a very high temperature or feels hot, cold or shivery, keeps being sick and cannot keep fluid down, has diarrhea that lasts for over a week or has signs of dehydration, will not stop crying and is very distressed, or is refusing to feed. ¹ The NHS also says to see a GP if a baby is not improving after trying things to ease reflux, gets reflux for the first time after they are 6 months old, is older than 1 and still has reflux, or is not gaining weight or is losing weight. ¹**

**A quick, honest note:** we're not medical professionals - everything here was researched by us from the public sources listed at the bottom of this page, and it isn't professional advice. Read our full note ↓

What is baby reflux?

Baby reflux, also called spit-up or gastroesophageal reflux (GER), is the movement of stomach contents up into the esophagus and sometimes out through the mouth and nose, according to the American Academy of Pediatrics. ³ The NHS puts it simply: "Reflux is when a baby brings up milk, or is sick, during or shortly after feeding." ¹ The NHS says this usually happens because the ring of muscle inside the baby's food pipe (oesophagus) can be weak, which allows milk to come back up easily. ¹ MedlinePlus explains that a ring of muscle called the lower esophageal sphincter normally prevents stomach contents from moving up, and that if this muscle does not close well, food can leak back into the esophagus. ² In MedlinePlus's words, "A small amount of gastroesophageal reflux is normal in young infants." ² MedlinePlus adds that ongoing reflux with frequent vomiting can irritate the esophagus and make an infant fussy. ² The American Academy of Pediatrics says that when reflux is associated with other symptoms, or if it lasts beyond infancy, it is considered a disease known as gastroesophageal reflux disease, or GERD. ³

When does baby reflux get better?

The NHS says infant reflux usually starts before a baby is 8 weeks old and gets better by the time they are 1 year old. ¹ The American Academy of Pediatrics says GER usually begins at about 2 to 3 weeks of age and peaks between 4 and 5 months old, and that for most babies born full-term, symptoms go away by the time they are 9 to 12 months old. ³

How can I help my baby with reflux?

The American Academy of Pediatrics says feeding and position changes are recommended as first-line therapy for both GER and GERD. ³ The NHS says to make sure a baby sleeps flat on their back, that they should not sleep on their side or front, and not to raise the head of their cot or Moses basket. ¹ MedlinePlus agrees, saying that despite reflux, "your infant should still sleep on their back, unless your provider suggests otherwise." ² The American Academy of Pediatrics also says never to add solids to the bottle unless a pediatrician advises it. ³

When should I see a doctor about my baby's reflux?

The NHS says to see a GP if a baby is not improving after trying things to ease reflux, gets reflux for the first time after they are 6 months old, is older than 1 and still has reflux, or is not gaining weight or is losing weight. ¹ The NHS says to ask for an urgent GP appointment or call NHS 111 if a baby has vomit that is green or yellow or has blood in it, is projectile vomiting, has blood in their poo, has a swollen or tender tummy, has a very high temperature or feels hot, cold or shivery, keeps being sick and cannot keep fluid down, has diarrhea that lasts for over a week or has signs of dehydration, will not stop crying and is very distressed, or is refusing to feed. ¹

Frequently asked questions

What is baby reflux?

The American Academy of Pediatrics says spit-up, also called reflux or gastroesophageal reflux (GER), is the movement of stomach contents into the esophagus and sometimes out through the mouth and nose. ³ MedlinePlus says a small amount of gastroesophageal reflux is normal in young infants. ² The NHS says reflux usually happens because the ring of muscle inside the baby's oesophagus can be weak, which allows milk to come back up easily. ¹

When does baby reflux get better?

The American Academy of Pediatrics says GER usually begins at about 2 to 3 weeks of age, peaks between 4 and 5 months, and goes away for most full-term babies by 9 to 12 months. ³ The NHS says reflux usually gets better by the time a baby is 1. ¹

How can I help my baby with reflux?

The American Academy of Pediatrics says feeding and position changes are recommended as first-line therapy for both GER and GERD. ³ The NHS says to make sure a baby sleeps flat on their back and not to raise the head of their cot or Moses basket. ¹ The American Academy of Pediatrics says never to add solids to the bottle unless a pediatrician advises it. ³

When should I see a doctor about my baby's reflux?

A note from us

We're the team behind Yael & Michal. We are not doctors, nurses, lactation consultants, or psychologists, and nothing here is professional advice.

Everything above was researched by us from public, reputable sources - we name and link every one of them below - and summarized as carefully as we could, as a free resource for other mothers. We do this because we wished something like it had existed for us.

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Sources

NHS (National Health Service, UK). https://www.nhs.uk/conditions/reflux-in-babies/ (retrieved 2026-07-10).
MedlinePlus (U.S. National Library of Medicine). https://medlineplus.gov/ency/article/001134.htm (retrieved 2026-07-10).
HealthyChildren.org (American Academy of Pediatrics). https://www.healthychildren.org/English/health-issues/conditions/abdominal/Pages/GERD-Reflux.aspx (retrieved 2026-07-10).