Yes, shaking formula introduces air bubbles that your baby can swallow during feeding, which often leads to gas and discomfort. The good news is that this is one of the easier causes of infant gas to fix, and a few simple changes to how you prepare bottles can make a noticeable difference.
How Shaking Creates Gas
When you vigorously shake a bottle of formula, the motion traps tiny pockets of air throughout the liquid, creating the foam and bubbles you see at the top. This doesn’t change the nutritional value of the formula at all. But when your baby drinks, those air bubbles travel into the stomach along with the milk. The swallowed air builds up and needs to go somewhere, which means more burping, more fussiness, and a baby who seems uncomfortable during or after feeds.
It’s worth understanding that not all infant gas comes from the same place. Burps come from swallowed air, which is exactly what shaking introduces. Gas that passes as flatulence has a different origin: it’s produced by normal gut bacteria breaking down undigested milk in the intestines. So if your baby is mostly burpy and uncomfortable during feeds, swallowed air from bubbles (or from crying, or a poor latch on the nipple) is a likely culprit. If the issue is more about straining and fussiness between feeds, the cause may be digestive rather than air-related.
Signs Your Baby Has Swallowed Air
Babies with gas from swallowed air tend to squirm, ball up their legs, grunt, turn red, and sometimes cry until they produce a big burp or pass gas. This can happen during a feed, right after, or even wake them from sleep. It looks alarming, but according to Children’s Hospital of Philadelphia, if your baby is feeding well, gaining weight normally, and passing soft stools that are green, yellow, or brown, then the grunting, straining, and crying with gas is harmless. It doesn’t indicate a belly problem or formula intolerance.
That said, “harmless” doesn’t mean comfortable. If you can reduce the amount of air your baby swallows, you’ll likely see less of this fussiness.
How to Prepare Formula With Less Air
The simplest fix is to stop shaking the bottle entirely. Instead, try swirling the bottle in a gentle circular motion. This dissolves powder more slowly but introduces far fewer air bubbles. You can also stir the formula with a clean utensil, which keeps air incorporation to a minimum.
If you do shake the bottle (some formulas are hard to mix otherwise), let it sit for a few minutes before feeding. The bubbles will gradually rise to the surface and pop. You’ll be able to see this happen: the foamy layer at the top shrinks as the formula settles. Even two to five minutes of resting makes a difference.
A few other preparation tips that help:
- Use warm water. Formula dissolves more easily in warm water than cold, so you won’t need to shake as hard to get the powder to mix.
- Add powder to water, not water to powder. Pouring water on top of a scoop of powder tends to create more clumps that require vigorous shaking to break up.
- Try ready-to-feed formula. Pre-mixed liquid formula requires no shaking at all, which eliminates the air problem entirely. It costs more, but it’s useful during periods when gas is particularly bad.
Bottles That Reduce Air Intake
Even if you prepare formula perfectly, babies can still swallow air during the act of feeding itself. As a baby sucks, a vacuum forms inside the bottle, and when that vacuum releases, it pulls air into the milk. Anti-colic bottles are designed to solve this. They use internal vent systems that equalize pressure inside the bottle, so air flows through the vent rather than through the milk and into your baby’s mouth.
Nipple flow rate matters too. If the nipple flows too fast, your baby may gulp and swallow air trying to keep up. If it’s too slow, they may suck harder and pull in air around the edges of the nipple. Matching the nipple size to your baby’s age and feeding pace helps reduce air intake from both directions. Holding the bottle at an angle so the nipple stays full of milk (rather than half-air) also makes a difference.
Gas Drops and Burping
Over-the-counter gas drops containing simethicone work by lowering the surface tension of gas bubbles in the stomach and intestines. This causes small bubbles to merge into larger ones that are easier to burp up or pass. Simethicone isn’t absorbed into the body, so it stays in the digestive tract and passes through. You can add these drops directly to a prepared bottle of formula before feeding, which also helps break down bubbles in the formula itself.
Frequent burping during feeds is the other reliable tool. Pausing every two to three ounces to burp gives swallowed air a chance to escape before it travels deeper into the digestive tract, where it causes more discomfort. Some babies need to be burped more often than that, especially if they’re fussy eaters or tend to gulp. Holding your baby upright for 10 to 15 minutes after a feed also helps trapped air rise and release.
When Gas Is Not About Air Bubbles
If you’ve switched to gentler mixing, tried anti-colic bottles, and burp frequently but your baby is still very gassy, the cause may not be swallowed air. Some babies produce more intestinal gas because their digestive systems are still maturing. The normal bacteria in an infant’s gut produce gas as they break down undigested milk sugars, and this process is especially active in the first few months of life.
Formula composition can also play a role. Babies who are sensitive to cow’s milk protein or lactose may experience more gas, along with other symptoms like unusually watery or mucousy stools, rashes, or excessive spitting up. In these cases, the issue is the formula itself rather than how it’s prepared. A switch to a hydrolyzed or lactose-reduced formula can help, but that’s a conversation to have with your pediatrician based on your baby’s specific symptoms.