Alimentum is a hypoallergenic infant formula made by Abbott (under the Similac brand) that uses predigested casein protein instead of the intact cow’s milk protein found in standard formulas. It’s designed for babies who have cow’s milk protein allergy, sensitivity to intact protein, or colic symptoms tied to protein sensitivity. Because the protein is already broken down into very small pieces, most babies with cow’s milk allergy can tolerate it without an allergic reaction.
How Alimentum Differs From Standard Formula
Standard infant formulas contain whole cow’s milk proteins that a baby’s digestive system has to break down on its own. For most babies, this works fine. But roughly 2 to 3 percent of infants are allergic or sensitive to these proteins, which can trigger symptoms ranging from excessive crying and gas to skin rashes, bloody stools, and vomiting.
Alimentum solves this by using hydrolyzed casein, a milk protein that has been chemically broken apart into much smaller fragments, then supplemented with individual amino acids (the building blocks of protein). This process is called extensive hydrolysis, and it’s thorough enough that the immune system of most allergic babies no longer recognizes the protein as a threat. The formula also replaces lactose with sugar and modified tapioca starch as its carbohydrate sources, making it suitable for babies with lactose sensitivity on top of protein issues.
Who It’s Made For
Pediatricians typically recommend Alimentum for a few overlapping situations:
- Cow’s milk protein allergy (CMPA): The most common reason. Babies with confirmed or suspected CMPA need a formula where the protein won’t trigger their immune system.
- Colic linked to protein sensitivity: Some colicky babies cry excessively because they’re reacting to intact protein. Abbott states that Alimentum starts reducing excessive crying in most of these infants within 24 hours.
- General protein intolerance: Babies who struggle to digest intact protein from any source, not just cow’s milk, may do better on a predigested formula.
- Lactose sensitivity: Because Alimentum doesn’t use lactose, it works for babies who have trouble with this milk sugar.
It comes in both powder and ready-to-feed liquid forms, plus a version formulated for toddlers. All are classified as nutritionally complete, meaning they can serve as a baby’s sole source of nutrition.
How It Compares to Other Specialty Formulas
Alimentum sits in the middle tier of specialty formulas. It’s classified as a Class II extensively hydrolyzed formula, the same category as its closest competitor, Nutramigen (made by Mead Johnson). Both use broken-down casein protein and target the same conditions. The choice between them often comes down to which one a particular baby tolerates better in terms of taste, digestion, and fussiness.
For babies with more severe allergies who still react to extensively hydrolyzed formulas, there’s a step up: amino acid-based formulas like EleCare (also made by Abbott), PurAmino, and Neocate. These contain no intact protein fragments at all, only individual amino acids. They’re reserved for the small percentage of babies whose immune systems react even to the tiny protein pieces in formulas like Alimentum. Amino acid formulas tend to cost more and taste worse, so doctors usually try an extensively hydrolyzed option first.
Taste, Smell, and Getting Your Baby to Accept It
One thing parents notice immediately is that Alimentum smells and tastes noticeably different from standard formula. The hydrolysis process that breaks down the protein also gives it a bitter, somewhat unpleasant flavor that adults find off-putting. Babies transitioning from a regular formula may initially refuse it.
If your baby resists the switch, a gradual transition can help. Mix a small amount of Alimentum into the familiar formula and slowly increase the ratio over several days, giving your baby’s palate and digestive system time to adjust. That said, if your baby is having an allergic reaction to their current formula, a cold-turkey switch is sometimes necessary, and most babies will accept the new formula once they’re hungry enough. Starting the new formula at the first feed of the day, when your baby is hungry but not yet fussy, can improve acceptance and gives you the rest of the day to watch for any reaction.
Patience matters here. Acceptance of a new formula can be slow, and it may take several attempts before your baby drinks a full bottle without protest.
What to Expect After Switching
If your baby’s symptoms are caused by cow’s milk protein sensitivity, you can expect to see improvement relatively quickly. Many parents report less crying and visible discomfort within the first day or two. Digestive symptoms like bloody stools or persistent vomiting generally take a bit longer to fully resolve, sometimes a week or two, as inflammation in the gut heals.
You’ll also notice changes in your baby’s stool. Hydrolyzed formulas tend to produce looser, greenish stools with a stronger smell. This is normal and not a sign that the formula isn’t working. It’s simply a byproduct of how the predigested protein is absorbed.
If your baby’s symptoms don’t improve after two weeks on Alimentum, that’s worth discussing with your pediatrician. A small number of babies with severe cow’s milk protein allergy react even to extensively hydrolyzed formulas and need to move to an amino acid-based option instead.
Cost and Availability
Alimentum costs significantly more than standard infant formula, typically two to three times the price. This is true of all extensively hydrolyzed formulas, not just this brand. The specialized manufacturing process that breaks down the protein drives up production costs. Ready-to-feed versions cost even more than the powder, though some parents find the liquid easier to use and report that their babies tolerate it slightly better.
Some insurance plans and state WIC programs cover hypoallergenic formulas when a doctor documents a medical need. If cost is a concern, ask your pediatrician for a letter of medical necessity, which can sometimes unlock insurance coverage or access to WIC-supplied formula. Alimentum is widely available at major retailers, pharmacies, and online, though specialty formulas can occasionally run low during supply chain disruptions.