Not reliably. Hydrolyzed formulas break cow’s milk proteins into smaller peptides, and they have a real job: feeding babies who have been diagnosed with cow’s milk allergy, usually with the extensively hydrolyzed kind. But large reviews have not shown that partially or extensively hydrolyzed formulas prevent eczema, asthma or food allergy in babies who do not already have a milk allergy, and the American Academy of Pediatrics and Australia’s clinical allergy society no longer recommend them for that purpose. For a healthy baby, a standard formula is the usual choice, and allergy prevention efforts are better spent on timely introduction of foods such as peanut and egg, guided by your pediatrician.
What hydrolyzed means on the label
MedlinePlus describes partially hydrolyzed formula as formula whose milk protein has been broken into smaller pieces, which in theory makes it easier to digest; it is commonly used for formula-fed babies with gas, fussiness and crying. Hypoallergenic formulas, also called protein hydrolysate formulas, may help babies with milk protein allergies and are generally much more expensive. MedlinePlus adds that almost all babies do well on standard cow’s milk-based formulas.
The difference between the two is the size of the peptides left after processing. A 2022 review in Foods explains that there is no uniform definition, but extensively hydrolyzed formulas mostly contain peptides smaller than about 3 kilodaltons, while partially hydrolyzed formulas mostly contain peptides under about 5 kilodaltons and can include larger ones. Breaking the proteins down is meant to lower their allergenicity while keeping the formula nutritious, the review says, and it also notes large differences between products, and even between batches.
What the prevention studies found
A 2016 systematic review and meta-analysis in The BMJ, commissioned to inform UK infant feeding guidelines, examined 37 trials with more than 19,000 participants. It found no consistent evidence that partially or extensively hydrolyzed formulas lower the risk of allergic or autoimmune disease, even in babies at high risk. Most studies of allergic outcomes had evidence of conflict of interest and a high or unclear risk of bias, and there were signs of publication bias for eczema and wheeze. The authors said their findings did not support a health claim the U.S. Food and Drug Administration had allowed for a partially hydrolyzed formula and eczema.
A 2018 Cochrane review reached a similar conclusion. Across trials of prolonged feeding with hydrolyzed formula instead of cow’s milk formula, it found no difference in allergic disease overall or in asthma, eczema, rhinitis, food allergy or cow’s milk allergy, with very low-quality evidence for every outcome. The only hint of benefit, short-term use of an extensively hydrolyzed formula in the first days after birth to prevent cow’s milk allergy, was also rated very low quality, and the authors called for more trials before it is put into practice.
What pediatric and allergy groups now advise
A 2019 American Academy of Pediatrics clinical report concluded there is a lack of evidence that partially or extensively hydrolyzed formula prevents allergic disease. The same report found no evidence that delaying allergenic foods beyond 4 to 6 months prevents allergies, and said early introduction of peanut may prevent peanut allergy. The 2026 guideline from the Australasian Society of Clinical Immunology and Allergy states that breast milk substitutes based on hydrolyzed milk protein, soy or other proteins are not recommended for allergy prevention. It advises introducing well-cooked egg and peanut soon after solids begin, usually around 6 months and not before 4 months.
When a hydrolyzed formula makes sense
The picture changes once a milk allergy is diagnosed. The Foods review notes that an extensively hydrolyzed formula is generally recommended for babies with cow’s milk allergy who cannot be fully breastfed, with amino acid-based formula as an alternative for severe allergy or when the hydrolyzed formula is not tolerated. If you suspect a reaction to formula, or your baby has rashes or wheezing you think might be allergic, talk with your pediatrician before switching, so the formula matches a diagnosis rather than a marketing claim.
By The Everyday Brief · AI-assisted editorial. Drafted with AI research assistance; claims checked against the linked sources (fetched 2026-10-06 PT). Not medical advice.
Sources
- Boyle RJ, et al. Hydrolysed formula and risk of allergic or autoimmune disease: systematic review and meta-analysis. BMJ, 2016.
- Osborn DA, Sinn JK, Jones LJ. Infant formulas containing hydrolysed protein for prevention of allergic disease. Cochrane Database of Systematic Reviews, 2018.
- Greer FR, et al. The effects of early nutritional interventions on the development of atopic disease in infants and children. Pediatrics (American Academy of Pediatrics clinical report), 2019.
- Vale SL, et al. ASCIA guideline: infant feeding for food allergy prevention. Clinical and Experimental Allergy, 2026.
- Maryniak NZ, et al. Alternatives to cow’s milk-based infant formulas in the prevention and management of cow’s milk allergy. Foods, 2022.
- MedlinePlus (U.S. National Library of Medicine): Infant formulas