Once a physician recommends a particular formula, moms have other choices to face. Most moms use a combination of the forms offered. Powder is usually the least expensive, but can be time-consuming to prepare. Powdered formula must be mixed with a specified amount of sterilized water and can be made one bottle, or several bottles, at a time. Powder must be used within 1 month of opening the container.
Concentrated liquids are also economical and convenient.
Bottles are prepared by mixing equal parts of formula and sterilized water. Opened formula should be refrigerated and stored in a sealed container and used within 48 hours. These formulations need no measuring or mixing and are the most convenient. They are also the most expensive. These, too, must be used within 48 hours after opening.