Spit-Up or Vomit—How Can You Tell the Difference?

Your baby just spit up. Or maybe vomited. You’re not sure which it was or whether you should be worried. Baby spit-up isn’t usually an issue. 

Also known as reflux, spit-up is simply the flow of food from your little one’s stomach to their mouth.  

It’s common, not painful, and might happen from time to time until your baby is about a year old. Baby spit-up is often just the result of a still-developing digestive system or overfeeding. 

The difference between spit-up and vomit is outlined below. If you have further questions or concerns, contact your healthcare provider.  

Spitting up is a common occurrence in healthy infants early in life. This is partly because of immaturity of their digestive system. It’s relatively harmless and usually resolves as the digestive system matures, when your baby reaches 12 to 14 months of age.    

Spit-up is sometimes called by other terms like “regurgitation” and “gastroesophageal reflux.” They’re just fancier ways of saying spit-up, with a minor difference. Regurgitation and reflux refer to the backwards movement of the stomach (gastric) contents up into the esophagus—and at times into the mouth. When the contents of your baby’s tummy spill out of their mouth, it’s called spit-up.

At birth, your baby’s tummy is about the size of a small marble. After 3 days, it is about the size of a ping-pong ball, but still can’t hold much.¹ Until they are about 4 months old, most babies’ tummies can hold only small amounts of milk at a time. Too much milk during feedings can cause your baby to spit up or be fussy.  

Babies also have less developed muscles in the upper esophagus, which makes it easier for fluids to flow back up from the stomach.  

Spitting up can also happen when your baby burps (called a wet burp) or swallows too much air. It isn’t painful to your baby, and most babies don’t even realize they have done it.

As long as your baby is healthy and gaining weight, spit-up should be seen as just a normal part of infancy. 

It may look like a lot when it’s on your shirt, but the amount of liquid your baby spits up isn’t as much as you think. Usually, it’s just 1 or 2 tablespoons at a time. If your baby spits up more than this—or if their spitting up is the effect of respiratory events like choking, coughing, or wheezing—ask your pediatrician if there is a reason to be concerned. 

To help your baby spit up less often, here are a few things you can try: 

• Hold baby in a more upright position while feeding 
• Burp baby after every 1 to 2 ounces while feeding 
• If you bottle-feed your baby, make sure the hole in the bottle's nipple is not too large. If it is too large, consider replacing the nipple with a new one 
• Keep your baby upright after eating. Laying them flat on a full stomach can lead to spit-up 
• Avoid too much activity for your baby immediately after eating 
• Feed your baby less food, but more often 

Your newborn will probably be hungry 6 to 10 times in a 24-hour period. As a baby grows, so does their stomach, so your baby should begin to eat more at each feeding and eat less often, as the chart below shows.

The best way to feed your baby is to allow them to take as much as they seem to need. If your baby's fussy and has not been fed in more than 2 hours, it is probably time for a feeding.  

When spitting up begins to make your baby uncomfortable, and more liquid than usual comes up with greater force, this is probably vomit. When a baby vomits more than once, it’s usually caused by a virus. Viruses usually aren’t dangerous, but they can cause your little one to get dehydrated. If your baby is less than 1 year of age, they are at more risk for dehydration. Consult your healthcare professional immediately if you think your baby might be dehydrated.  

When your baby has a sudden bout of vomiting (with or without diarrhea), it usually means they have a virus. A virus usually isn’t dangerous, but it can lead to dehydration, which can be a serious problem. It’s important to know these signs of dehydration in your baby: 

• Fewer wet diapers than normal 
• Seems very tired or weak 
• Has tearless, sunken eyes
• Has dry skin and little saliva  

The younger your baby, the more concerned you should be about dehydration. There are things you can do to help when your baby is ill. Replace the fluids your baby is losing by giving them small, frequent feedings. In some cases, an oral rehydration solution such as Pedialyte^® may be recommended. Check with your healthcare provider for advice. 

Although it can be alarming, an occasional vomiting episode is usually nothing to worry about. However, if your baby vomits often, this can be a sign of reflux disease, intestinal obstruction, infection, or a protein allergy. Get in touch with your pediatrician if your baby's usual spit-up: 

• Increases in amount or force 
• Causes choking or respiratory difficulty like wheezing or coughing 
• Leads to other issues including discomfort, fussiness, poor weight gain, or weight loss 
• Is accompanied by a fever, diarrhea, bloody mucus, or a bloated tummy 
• Is green
• Is “projectile,” meaning very sudden and with great force  

Repeated vomiting in babies between 2 weeks and 4 months of age can be a sign of a blockage at the stomach. Contact your healthcare professional immediately if your baby vomits repeatedly. 

Consult your pediatrician before changing your baby’s formula. 

Similac offers several infant formulas for sensitive tummies that are designed to help ease common tummy troubles like fussiness and gas due to lactose sensitivity. For help choosing a formula, check out our Tummy Trouble Tool.

Questions about formula feeding? See our Frequently Asked Questions.

References: 1. Spangler AK, et al. J Hum Lact. 2008;24(2):199-205. 2. Behrman RE, et al. Nelson Textbook of Pediatrics. 16th ed. Philadelphia: WB Saunders Co; 2000:165. 3. Samour PQ, et al. Handbook of Pediatric Nutrition. 3rd ed. Sudbury, MA: Jones and Bartlett Publishers; 2005:90. 4. Fomon SJ. Infant Nutrition. 2nd ed. Philadelphia: WB Saunders Co; 1974:24.