No single formula is proven to cure colic, but extensively hydrolyzed casein-based formulas have the strongest evidence for reducing crying time in formula-fed infants. These formulas break milk proteins into tiny fragments that are easier to digest and less likely to trigger a reaction. If your baby cries for more than three hours a day, more than three days a week, for three weeks or longer, that meets the clinical definition of colic, and a formula change is one of the first practical steps worth trying.
Why Formula Type Matters for Colic
Standard infant formulas use intact cow’s milk proteins, primarily whey and casein. Some colicky babies struggle with these proteins, particularly one called beta-lactoglobulin. It’s the largest allergen in cow’s milk and the major component of cow’s milk whey protein, yet it doesn’t exist in human breast milk. When an infant’s immature digestive system encounters it, the result can be gas, discomfort, and prolonged crying.
Hydrolyzed formulas address this by breaking those proteins down before they reach your baby’s gut. The degree of breakdown matters. Partially hydrolyzed formulas chop proteins into smaller pieces. Extensively hydrolyzed formulas break them down even further, into fragments small enough that the immune system is unlikely to recognize them as a threat. For colic specifically, extensively hydrolyzed casein-based formulas tend to outperform whey-based options. Research has found that colic symptoms recur in about 75% of infants given whey protein powders from cow’s milk, likely because of that beta-lactoglobulin content.
Extensively Hydrolyzed Casein Formulas
These are the formulas most commonly recommended when colic may be tied to cow’s milk protein sensitivity. The American Academy of Pediatrics has stated that partially hydrolyzed formulas are not hypoallergenic and should not be used for dietary management of colic caused by cow’s milk protein allergy. Extensively hydrolyzed casein formulas are the appropriate step up.
In clinical trials, researchers have used casein hydrolysate formulas in four-day crossover periods against standard cow’s milk formula, with measurable improvements in crying. These formulas taste more bitter than standard options and cost more, which are real trade-offs. But they remain the first-line formula change when colic is severe enough to warrant intervention.
Partially Hydrolyzed Formulas With Prebiotics
Partially hydrolyzed whey formulas occupy a middle ground. A randomized controlled trial of a partially hydrolyzed cow’s milk formula with an added prebiotic blend found that it did not reduce overall parent-reported fussiness compared to a control formula. However, it did significantly reduce crying and excessive crying over four weeks of use. So while these formulas may not eliminate the general irritability parents notice, they can take the edge off the worst episodes.
A separate trial tested a partially hydrolyzed formula with reduced lactose content and an added probiotic strain. After 28 days, infants on that formula cried an average of about 105 minutes per day, compared to 146 minutes per day in the control group, a reduction of roughly 42 minutes. That’s meaningful when you’re living through it, even if it doesn’t eliminate crying entirely.
The Role of Lactose
Some colicky babies have transient difficulty digesting lactose, the sugar naturally present in both breast milk and most formulas. Low-lactose or reduced-lactose formulas can help in these cases. The clinical trial mentioned above specifically combined reduced lactose content with hydrolyzed protein and a probiotic, and the combination produced a statistically significant drop in daily crying time. If your baby seems gassier and more uncomfortable after feeds, a formula with reduced lactose is worth discussing with your pediatrician, though removing lactose entirely isn’t necessary for most infants.
Amino Acid Formulas for Severe Cases
About 5% to 10% of infants who try extensively hydrolyzed formulas still don’t improve. Their allergy symptoms persist or their nutritional status doesn’t normalize. In these cases, amino acid-based formulas are the next option. These contain proteins broken down to their individual building blocks, making allergic reactions essentially impossible.
Amino acid formulas are also preferred upfront for infants with severe gastrointestinal symptoms, significant skin reactions like severe eczema, or failure to thrive. Studies following infants for six to nine months on amino acid formulas found significantly better height growth compared to extensively hydrolyzed formulas, making them particularly important when a baby isn’t gaining weight or length appropriately. These formulas are the most expensive option and are typically reserved for confirmed or strongly suspected cow’s milk protein allergy that hasn’t responded to other changes.
Why Soy Formula Isn’t the Answer
Many parents reach for soy formula as a first switch, but the AAP has stated that soy protein-based formula has no proven value in preventing or managing infantile colic. A significant percentage of infants who react to cow’s milk protein also react to soy protein, so switching to soy often doesn’t solve the problem. The AAP considers parental counseling about the natural course of colic more valuable than a switch to soy.
What About Probiotics in Formula
Certain probiotic strains have shown promise for colic, but the evidence is strongest for breastfed infants, not formula-fed ones. A 2023 position paper from the European Society for Paediatric Gastroenterology, Hepatology and Nutrition found moderate evidence supporting a specific strain of Lactobacillus reuteri for managing colic in breastfed babies, given as five drops daily before a feeding. For formula-fed infants, the same group concluded there wasn’t enough evidence to make a recommendation either way.
Some formulas now include probiotics or prebiotics as added ingredients. The reduced-lactose hydrolyzed formula that cut crying by 42 minutes per day included a Lactobacillus reuteri strain, so the combination may offer benefits even if probiotics alone haven’t been proven in formula-fed babies. If you’re choosing between two similar formulas and one contains added probiotics, it’s a reasonable tiebreaker, but probiotics alone aren’t a substitute for the right protein base.
How Long to Wait After Switching
Give a new formula at least four days before judging whether it’s helping, though most pediatricians suggest a full one to two weeks for a clearer picture. Clinical trials typically measure outcomes at the four-week mark, which is when the most consistent improvements appear. Switching formulas every day or two doesn’t give any single option a fair chance and can make symptoms harder to track.
Keep a simple log of crying duration each day. This removes the guesswork and helps you spot real trends rather than relying on how a particularly bad afternoon felt. If crying time drops noticeably within two to four weeks, the formula is likely helping.
Signs It May Not Be Simple Colic
Colic is a diagnosis of exclusion, meaning it applies when nothing else explains the crying. Cow’s milk protein allergy can look very similar but comes with additional red flags: blood in the stool, persistent vomiting, diarrhea or constipation, and worsening fussiness specifically after feedings. These digestive symptoms typically start within the first week of a baby being exposed to cow’s milk protein.
If your baby has any of these signs alongside the crying, the issue is more likely a true allergy than simple colic, and the formula strategy shifts. An extensively hydrolyzed or amino acid formula becomes a medical necessity rather than just a comfort measure. Most colic resolves on its own between four and six months of age. If symptoms are getting worse rather than gradually improving as your baby approaches that window, that’s another reason to revisit the diagnosis with your pediatrician.