Why Is a Baby Spitting Up Curdled Milk?

Medically Reviewed by Dan Brennan, MD on April 11, 2023
3 min read

If your baby is spitting up after feeding, you might wonder if this is something you should be concerned about. Spitting up can be even more jarring when the milk has a curdled appearance.  

‌As long as your child is showing no other signs of illness, is alert, and is gaining weight, spit-up is not typically a cause for concern and generally slows down by 12 to 18 months of age. 

Spitting up refers to what happens in the first few months of your baby's life when they regurgitate some of their stomach contents. Because a baby's diet consists of primarily breast milk or formula, the spit-up is likely to be a white texture but can vary depending on how long after feeding your baby spits up. 

Spit up that looks like curdled milk is no reason to be alarmed, and there is an explanation. If your child spits up during or immediately after feeding, it is likely to have a smooth, milky texture. If your baby spits up after the milk has had time to mix with your baby's stomach acid, the spit-up is likely to appear curdled.  

Baby spit-up differs from vomit in that the flow of spit-up is usually slower and stays closer to the baby's body, while vomiting is more forceful and projectile and can indicate illness. If your child is vomiting, call your child's health care provider. 

There is a muscle ring between the stomach and the esophagus called the lower esophageal sphincter (LES). In babies, this muscle is not as developed as it is in adults and older children, resulting in frequent spitting up of stomach contents. Some babies spit up more than others, and it is important to remember that babies' stomachs are very small and can become full quickly. 

Parents often think that their babies are spitting up more than they actually are. A puddle of spit-up or a large spit-up stain can look like a lot of liquid, but it is important to consider how much liquid spreads. Imagine spilling just a tablespoon of water on a table. It would look like a lot more liquid than it actually is. 

If your baby is spitting up frequently, and you would like to try to reduce how much they are spitting up, there are a few things that you can try to see if they help: 

  • You can feed your baby in an upright or semi-upright position. 
  • You can try to feed your baby smaller amounts of milk in each feeding. 
  • If your baby is formula-fed, you may want to try a different formula to see if that helps 
  • If you are breastfeeding, you can try to experiment with your own diet to see if that helps. Some mothers find that eliminating dairy from their diet can reduce spit-up.

Though burping after feeding is frequently recommended to new parents, one study in 2015 found that burping increased the risk of spit-up in infants up to three months old. 

Avoid following advice that directs you to place your baby on their stomach while they sleep to prevent spitting up. It is important to place your baby to sleep on their back, as this reduces the risk of sudden infant death syndrome, also known as SIDS

Most of the time your baby spitting up is nothing to be concerned about as long as they are happy and gaining weight. However, there are instances where you should call your baby's health care provider. 

Some babies develop gastroesophageal reflux disease (GERD). GERD can cause health complications if left untreated. Consult your child's doctor if you notice any of the following symptoms, as they could indicate GERD or other serious health conditions: 

  • There is blood in your baby's spit-up.
  • Your baby's spit-up is green or yellow in color.
  • Your baby's spit-up resembles coffee grounds.
  • Your baby is refusing to eat.
  • Your baby suddenly begins spitting up after six months of age.
  • There is blood in your baby's stool.
  • Your baby has stopped gaining weight.
  • You notice a persistent cough or difficulty breathing.
  • Your baby seems lethargic.
  • The number of wet diapers has decreased suddenly.