Formula frustrations.

The mother of a pediatric patient was recently diagnosed with a rheumatologic illness, requiring her to take medications that would be dangerous to her nursing baby. She realized that she would need to feed her baby formula. She asked me, "What is the difference between the formulas at the grocery store? Which is the best kind for my baby?" The answer to this question is different for every baby. This article is a short guide for primary care pediatricians to help them understand the differences between common formulas.