The treatment of cow's milk protein allergy is the dietary elimination of cow's milk proteins. In non-breastfed infants and children less than 2 years of age, a substitute formula is mandatory as prescribed by several international scientific societies. Extensively hydrolyzed formulas are used as therapeutic formulas. An extensively hydrolysed formula is often a whey or casein based formula in which the protein has been chopped up in smaller pieces that are less allergenic. Because of high cross-reactivity (up to 80%) and nutritional inadequacy, the use of any other animal milk or soy-based formula is precluded.The infant should be maintained on an elimination diet until the child is between 9-12 months of age or at least for 6 months, whichever occurs first. In most cases, symptoms will improve substantially within 2-4 weeks if diagnosis is correct.