Neither Alimentum nor Nutramigen has a clear clinical advantage over the other for relieving gas. Both formulas use extensively hydrolyzed casein as their protein source, which means the milk protein is broken down into tiny fragments that are far less likely to trigger digestive reactions. The real differences between them come down to their carbohydrate sources, fat composition, and one notable added ingredient, and any of those factors could matter more or less depending on what’s driving your baby’s gas.
Why These Formulas Help With Gas
Gas in formula-fed infants often stems from difficulty digesting intact cow’s milk protein. When a baby’s gut reacts to those proteins, it can produce excess gas, bloating, fussiness, and sometimes visible discomfort during or after feeds. Both Alimentum and Nutramigen address this by pre-breaking the casein protein through a process called extensive hydrolysis. The protein fragments are small enough that most babies with cow’s milk protein sensitivity can tolerate them without the inflammatory gut response that produces gas.
That said, gas isn’t always caused by protein sensitivity. Air swallowing during feeds, immature digestive systems, and sensitivity to specific carbohydrates can all contribute. If your baby’s gas is primarily from cow’s milk protein, both formulas should help roughly equally. If the gas persists on one, the differences in their other ingredients are worth understanding.
How Their Ingredients Differ
The protein is essentially the same. Where these formulas diverge is in their carbohydrate and fat sources.
Nutramigen uses corn syrup solids as its primary carbohydrate in the powder version. Alimentum’s powder also contains corn-based carbohydrates. However, the Alimentum Ready-to-Feed version uses sugar (sucrose) and modified tapioca starch instead of corn-derived ingredients. This distinction matters if your baby has a corn sensitivity, which can mimic or worsen gas symptoms. For babies who seem to react to corn, Alimentum Ready-to-Feed is one of the few hypoallergenic options that avoids it entirely.
On the fat side, Alimentum Ready-to-Feed contains medium chain triglycerides (MCTs), a type of fat that is absorbed more easily because it doesn’t require bile salts for digestion. Nutramigen contains no MCTs. For babies with fat malabsorption issues, which can contribute to gas and loose stools, the MCTs in Alimentum may offer a small digestive advantage.
Nutramigen’s Probiotic: Does It Help?
Nutramigen includes Lactobacillus rhamnosus GG (LGG), a well-studied probiotic strain. This is the most notable difference between the two formulas on paper, and it sounds promising for gas relief. In practice, the evidence is less clear-cut.
A pilot study from the National Institutes of Health tested a casein hydrolysate formula with LGG against one without it in colicky infants. Babies in the probiotic group trended toward about 90 fewer minutes of crying and fussing per day by day 14. But the study found no significant difference in breath hydrogen levels between the two groups. Breath hydrogen is a direct marker of gas production in the gut. So while the probiotic may help with overall fussiness, it didn’t measurably reduce gas itself.
This doesn’t mean the probiotic is useless. LGG has good evidence for supporting gut barrier function and may help some babies with overall digestive comfort over time. But if gas specifically is your concern, the probiotic alone isn’t a strong reason to choose Nutramigen over Alimentum.
What Parents Commonly Report
Parent experiences vary widely, and neither formula consistently comes out ahead in online communities. Some parents report that Nutramigen causes looser stools and more frequent bowel movements, which some pediatricians consider a normal side effect of that formula. Others find their baby tolerates Nutramigen well but can’t handle Alimentum, or vice versa. Both formulas produce noticeably smelly stools and spit-up compared to standard formulas. That’s a normal result of the hydrolyzed protein and not a sign of a problem.
Most pediatricians suggest trying one formula for at least one to two weeks before switching, since it takes time for the gut to adjust. Increased gas in the first few days of a new formula is common and doesn’t necessarily mean the formula isn’t working. If gas and fussiness haven’t improved after two weeks, switching to the other is reasonable.
When the Formula Itself Isn’t the Fix
Two systematic reviews found some benefit from hypoallergenic formulas for colic, but the improvement needs to be weighed against the significantly higher cost of these formulas. Interestingly, research from the American Academy of Family Physicians found that counseling parents about infant crying patterns reduced colic symptoms more than any formula change. This doesn’t mean your baby’s gas isn’t real, but it does suggest that some degree of infant gassiness is developmental and resolves on its own regardless of formula choice.
If your baby still has significant gas, blood in the stool, or persistent discomfort on either Alimentum or Nutramigen, the next step is typically an amino acid-based formula like EleCare or PurAmino. These break protein down completely into individual amino acids rather than small fragments, and they’re designed for the small percentage of babies who react even to extensively hydrolyzed formulas.
Which One to Try First
If you suspect corn sensitivity or your baby has had reactions to corn-based ingredients, start with Alimentum Ready-to-Feed (not the powder, which still contains corn-derived ingredients). If corn isn’t a concern and you’d like the potential benefit of a built-in probiotic, Nutramigen is a reasonable first choice. If cost or availability is a factor, whichever one you can get consistently is the better option, since the core protein technology is the same in both.
The honest answer is that predicting which formula will work better for a specific baby is nearly impossible without trying it. The protein hydrolysis that does the heavy lifting for gas relief is equivalent in both. Everything else is a secondary factor that may or may not matter for your baby’s particular digestive situation.