Cow's milk (CM) allergy is the most common food allergy in children, affecting 2-3% of
infants. In formula-fed infants with CM allergy, extensively hydrolyzed or amino acid-based
infant formulas are typically recommended. These formulas are expensive and not palatable.
For older patients with CM allergy, the standard of care is avoidance of all CM products. The
investigators cared for a CM allergic patient who was able to tolerate partially hydrolyzed
whey formula (pHWF), which tastes better and is less expensive than extensively hydrolyzed or
amino-acid based formulas. There are likely other subjects who could similarly tolerate pHWF.
Furthermore, it is possible that taking pHWF could accelerate tolerance of CM. The
investigators aim to identify characteristics of CM allergic subjects who can tolerate pHWF
and assess the degree to which taking pHWF accelerates CM tolerance.