GUIDE
Both are extensively hydrolyzed casein-based formulas for babies with cow's milk protein allergy (CMPA). Nutramigen includes the probiotic LGG. Alimentum does not. Both work for most CMPA babies.
If your pediatrician has recommended a hypoallergenic formula, you're almost certainly looking at one of these two. They are the most widely prescribed extensively hydrolyzed formulas in the US. Here's how they actually compare — and what to know before you buy your first very expensive can.
"Hypoallergenic" in the context of infant formula has a specific meaning. It refers to formulas where the milk protein has been extensively broken down (hydrolyzed) into fragments small enough that the baby's immune system is unlikely to recognize them as cow's milk protein and mount an allergic response.
Both Alimentum and Nutramigen achieve this by taking casein — one of the two main proteins in cow's milk — and breaking it down into very small peptides. The resulting protein is functionally different from intact cow's milk protein. About 90% of babies with confirmed CMPA tolerate extensively hydrolyzed formulas successfully.
For the roughly 10% of CMPA babies who react even to extensively hydrolyzed formula, the next step is an amino acid-based formula (like EleCare or PurAmino), where the protein is broken down to its most basic building blocks. These are even more expensive and typically require a prescription or medical documentation.
| Feature | Alimentum | Nutramigen | Notes |
|---|---|---|---|
| Manufacturer | Abbott (Similac) | Reckitt (Enfamil) | The two largest US formula manufacturers |
| Type | Extensively hydrolyzed casein-based | Extensively hydrolyzed casein-based | Same fundamental approach — broken-down milk protein |
| Protein source | Casein hydrolysate (from cow's milk, broken into small peptides) | Casein hydrolysate (from cow's milk, broken into small peptides) | Both use casein as the protein base, extensively broken down |
| Carbohydrate source | Sucrose, modified tapioca starch | Corn syrup solids, modified corn starch | Different sugar sources — neither uses lactose |
| Fat sources | Safflower oil, MCT oil, soy oil | Palm olein, coconut, soy, high oleic sunflower oils | Alimentum includes MCT oil, which is easier to absorb |
| DHA / ARA | Yes | Yes | Both include DHA and ARA |
| Probiotics | No | Yes — LGG (Lactobacillus rhamnosus GG) | Key differentiator — LGG may accelerate tolerance development |
| Prebiotics | No | No | Neither includes prebiotics |
| MCT oil | Yes (33% of fat blend) | No | MCT oil is more easily absorbed — may benefit babies with fat malabsorption |
| Lactose-free | Yes | Yes | Both remove lactose, which can worsen GI symptoms in CMPA babies |
| Available forms | Powder, ready-to-feed | Powder, ready-to-feed, concentrate | Nutramigen has one additional form option |
The most significant ingredient difference between these two formulas is Nutramigen's inclusion of LGG (Lactobacillus rhamnosus GG), a probiotic strain. Here's what we know about it.
LGG (Lactobacillus rhamnosus GG) is one of the most studied probiotic strains in the world. In Nutramigen, it's included at a level intended to support the development of tolerance to cow's milk protein over time. The idea is that LGG helps modulate the immune response in the gut, potentially helping the baby 'outgrow' CMPA faster.
A 2017 study published in the Journal of Allergy and Clinical Immunology found that infants with CMPA who received extensively hydrolyzed casein formula with LGG had higher rates of cow's milk tolerance at 12 months compared to those who received formula without LGG. However, the study was industry-funded (by Mead Johnson, Nutramigen's manufacturer), and results have not been consistently replicated across all studies.
The AAP does not currently recommend one extensively hydrolyzed formula over another based on probiotic content. Both Alimentum and Nutramigen are considered appropriate first-line options for CMPA. The probiotic component of Nutramigen is an interesting area of research, but it hasn't changed the official recommendations.
| Item | Alimentum | Nutramigen | Standard Formula |
|---|---|---|---|
| Price per can (powder, ~12.1 oz) | $38-44 | $40-47 | $18-25 (store brand) |
| Price per can (ready-to-feed, 32 oz) | $10-12 | $10-13 | $6-8 |
| Estimated monthly cost (powder) | $190-264 | $200-282 | $72-100 |
| Estimated yearly cost (powder) | $2,280-3,168 | $2,400-3,384 | $864-1,200 |
| Premium over standard formula (yearly) | $1,416-1,968 | $1,536-2,184 | — |
There's no way around it: hypoallergenic formula is expensive. At $38-47 per can of powder, you're looking at $2,000-3,400 per year — roughly double to triple the cost of standard formula.
A few things that can help. WIC covers hypoallergenic formula when prescribed for a documented medical need. Some insurance plans will cover or reimburse part of the cost with a letter of medical necessity from your pediatrician. Both Abbott and Reckitt have manufacturer assistance programs and coupons. Amazon Subscribe & Save and warehouse clubs (Costco, Sam's Club) sometimes offer slight discounts on bulk purchases.
If cost is a barrier, talk to your pediatrician about documentation for insurance or WIC, and check the manufacturer websites for coupons. This is a medical need, not a luxury purchase, and financial assistance options exist.
When you're managing CMPA, having a clear record of feeds, symptoms, and how your baby is responding to formula changes makes a real difference. Log it in seconds, review it before appointments.
The hypoallergenic formula market is smaller but highly profitable. Here's what the marketing on both sides doesn't always make clear:
Most "gentle" and "sensitive" formulas are NOT hypoallergenic. If your baby has true CMPA, switching to Similac Sensitive, Enfamil Gentlease, or any "comfort" formula will not help. These formulas are partially hydrolyzed at best — the protein fragments are still large enough to trigger an immune response. They're designed for mild digestive discomfort, not for milk protein allergy. If your pediatrician says your baby needs a hypoallergenic formula, they mean Alimentum, Nutramigen, or an amino acid-based formula. Not "gentle."
CMPA is less common than you'd think. About 2-3% of infants have cow's milk protein allergy. Yet hypoallergenic formula is one of the fastest-growing segments of the formula market. A lot of babies are on hypoallergenic formula who don't actually need it — often because general fussiness, normal spit-up, or colic was attributed to a milk allergy without proper diagnostic evaluation. This matters because hypoallergenic formula costs 2-3x more and doesn't taste as good. If your baby doesn't have CMPA, they're getting an expensive, less palatable formula for no benefit.
The probiotic advantage of Nutramigen is real but overstated. The LGG probiotic in Nutramigen has shown some promise in accelerating tolerance development, but the primary study was industry-funded, and the AAP hasn't changed its recommendations based on it. Both formulas are equally effective at managing CMPA symptoms in the short term. The LGG is a reasonable tiebreaker, not a decisive advantage.
Getting a proper diagnosis matters. Before switching to a $40/can formula, ask your pediatrician to evaluate whether your baby truly has CMPA. The gold standard is an elimination and challenge test — removing cow's milk protein and reintroducing it to confirm the reaction. Jumping straight to hypoallergenic formula based on symptoms alone can lead to unnecessary expense and a formula that's harder for your baby to accept.
If your baby has one or more of these symptoms, talk to your pediatrician about CMPA evaluation. Blood in stool is the most suggestive sign and should always be evaluated.
These are common infant behaviors that are often mistaken for CMPA. If these are your baby's only symptoms, a hypoallergenic formula is unlikely to help. Talk to your pediatrician before switching.
Switching to a hypoallergenic formula is different from switching between standard formulas. Here's what to expect.
Extensively hydrolyzed formula smells and tastes significantly different from standard formula. The hydrolysis process creates a bitter, almost metallic taste. This is normal. It's the protein being pre-broken-down, which is the entire point. Most babies who genuinely need it will accept it within a few days, especially if they're uncomfortable on standard formula.
Unlike switching between standard formulas, the switch to a hypoallergenic formula is typically done immediately — not gradually. If your baby has CMPA, every feed of standard formula continues to cause a reaction. Your pediatrician will likely tell you to switch completely at the next feed.
GI symptoms usually improve within 3-5 days. Eczema may take 2-4 weeks. If you see no improvement after a full month, talk to your pediatrician — you may need an amino acid-based formula (like EleCare or PurAmino) for babies who can't tolerate even extensively hydrolyzed protein.
This is one of those times when tracking really pays off. Note the date of the switch, log each feed, and record any symptoms (blood in stool, rash, vomiting, fussiness level). When you see your pediatrician at follow-up, having this data makes the conversation much more productive than trying to remember.
If your baby has CMPA, even a small amount of intact cow's milk protein can trigger a reaction. Don't mix hypoallergenic formula with standard formula during the transition. It's all or nothing.
Hypoallergenic formula should always be used under medical guidance. Talk to your pediatrician in these situations:
Before starting a hypoallergenic formula — to confirm the diagnosis and rule out other causes of your baby's symptoms. A proper evaluation can save you significant money and ensure your baby gets the right formula for their actual needs.
If symptoms don't improve after 2-4 weeks on extensively hydrolyzed formula — your baby may need an amino acid-based formula, or the symptoms may not be caused by CMPA at all.
If your baby refuses the formula consistently — while most babies accept hypoallergenic formula within a few days, some struggle. Your pediatrician can offer strategies or may suggest trying the other brand, as some babies have a preference.
If you need help with cost — your pediatrician can provide a letter of medical necessity for insurance coverage, document the need for WIC, or connect you with manufacturer assistance programs.
If you're wondering when to try reintroducing standard formula — most babies outgrow CMPA by age 1-2. Your pediatrician can guide a supervised reintroduction when the time is right. Don't attempt this on your own.
For more on how to tell whether your baby is eating enough on their new formula, see our guide on adequate intake signs. For a broader comparison of formula types, see our store brand vs. name brand formula guide.
Alimentum and Nutramigen are both excellent options for babies with confirmed CMPA. They use the same fundamental approach (extensively hydrolyzed casein), they both work for about 90% of CMPA cases, and they cost about the same (which is a lot).
If you want a probiotic with emerging evidence for faster tolerance development, Nutramigen's LGG is a reasonable differentiator. If your baby has fat malabsorption issues, Alimentum's MCT oil content may be an advantage. If neither of those factors applies, the choice comes down to which one your baby tolerates better — and you may need to try both to find out.
The most important thing is getting the diagnosis right first. If your baby genuinely has CMPA, either formula will help. If they don't, neither will — and you'll be spending triple on formula your baby doesn't need.
This guide is for informational purposes only and is not a substitute for professional medical advice. If you suspect your baby has cow's milk protein allergy, please consult your pediatrician for proper diagnosis and treatment.
