Proper hygiene, handling, and storage are important when preparing infant formula. Failure to follow these instructions could result in severe harm. Powdered infant formulas are not sterile and should not be fed to premature infants or infants who might have immune problems unless directed and supervised by your babys doctor. Use water that has previously been heated at a full rolling boil for 5 minutes. Allow the water to cool and follow mixing instructions carefully. Use only the scoop enclosed in this tin to measure Similac Total Comfort 2. If you prepare more than one feeding, it must be refrigerated at 2-4 °C and used within 24 hours. Once feeding begins, use within one hour or discard.