how long is formula good once opened
Even properly refrigerated liquid formula should be used within 48 hours; if you've made a batch from powdered formula, you should use it within 24 hours. Remaining powdered formula should be used within a month after opening. Any formula left in the bottle an hour after your baby has started feeding should be discarded, so try not to fill the bottle with more than he usually takes. And as with any food, particularly one meant for a baby: When in doubt, throw it out. Contributing editor Heidi Murkoff is the coauthor of the bestselling What to Expect When You're Expecting (Workman) and the author of the What to Expect Kids series of children's books (HarperCollins).