My five-month-old breaks out in a rash when I feed him milk-based formulas. When I tried switching to soy formulas he threw up. Even when breastfed exclusively, he still has skin problems. Is there any other kind of formula I can try?
Once you have tried both milk-based and soy-based formulas, you are left with the hypoallergenic category. Two examples are Alimentum and Nutramagen. The protein components in these formulas have been predigested into basic amino acids. They are also significantly more expensive than the others and are designed for infants with protein allergies or significant intestinal problems.
Breaking out in a rash after milk-based formulas may or may not reflect an allergy. Throwing up after one without other symptoms is less likely to be a true allergy. It could also be an intolerance to the taste or texture of the formula but not necessarily the ingredients.
I suggest that you see your pediatrician about the problem. There are blood tests that can be done to distinguish true allergies from other problems.