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Be sure to avoid exposure to heat or extreme cold. Temperatures between 55 and 75 degrees Fahrenheit are a good rule of thumb. Avoid storing them in direct sunlight. Store opened powder formula in a cool, dry place with the lid securely in place. Powdered formula should never be stored in the refrigerator, as the humidity can cause the powder to clump. Place any opened ready-to-feed liquid formula in a sealed container and discard any unused portions after 48 hours. Store opened liquid concentrate formula in a covered container and refrigerator immediately after opening. Throw any unused mixed portions with in 24 hours of preparation.

Summary:
Keep unopened formula containers at room temperature. Store powder. Store liquid ready-to-eat formula. Store liquid concentrate formula.