An unopened tin of Kendamil formula lasts about two years from the manufacture date, which is printed on the bottom of the can. Once you open the tin, you have four weeks to use the powder. And once you mix a bottle, the clock tightens considerably: two hours at room temperature, or one hour from the moment your baby starts drinking.
How Long a Prepared Bottle Lasts
A freshly mixed bottle of Kendamil is safe at room temperature for up to two hours. If your baby has already started feeding from it, that window shrinks to one hour. After either limit, the bottle should be discarded. Bacteria from your baby’s mouth enter the formula during feeding, and warm liquid is an ideal environment for those bacteria to multiply quickly.
If you prepare a bottle but your baby isn’t ready to eat yet, you can place it in the refrigerator right away and use it within 24 hours. This is consistent with CDC guidelines for all powdered infant formula. Just be sure to refrigerate it promptly rather than letting it sit out first. Once you rewarm a refrigerated bottle and your baby begins drinking, the same one-hour rule applies.
Never freeze prepared formula. Freezing changes the texture and can cause the fats and proteins to separate, making the formula inconsistent and potentially difficult for your baby to digest.
How Long an Opened Tin Lasts
Once you break the seal on a tin of Kendamil powder, use it within four weeks. Kendamil suggests writing the date you opened it directly on the tin so you don’t lose track. After four weeks, the powder can absorb moisture from the air and degrade in quality, even if it looks and smells fine.
Store the opened tin in a cool, dry place with the lid tightly closed. A kitchen cabinet away from the stove or dishwasher works well. Do not store formula powder in the refrigerator. The humidity inside a fridge can cause the powder to clump and spoil faster. If you prefer to transfer the powder into a separate container, Kendamil recommends an airtight glass food storage container with the opening date written on the lid.
How Long an Unopened Tin Lasts
A sealed, unopened tin of Kendamil is good for roughly two years from the date of manufacture. Check the expiration date stamped on the bottom of the can before using it. Store unopened tins in a cool, dry indoor location. Garages, cars, and outdoor sheds expose the formula to temperature swings and humidity that can compromise it well before the printed date.
Quick Reference by Situation
- Unopened tin: Up to 2 years from manufacture (check expiration date on can)
- Opened tin: 4 weeks, stored in a cool, dry place with the lid sealed
- Prepared bottle, room temperature: 2 hours from mixing
- Prepared bottle, refrigerated immediately: 24 hours
- Bottle your baby has started drinking: 1 hour, then discard
- Leftover formula in a bottle after feeding: Discard immediately
Extra Precautions for Newborns and Preemies
If your baby is under two months old, was born premature, or has a weakened immune system, the CDC recommends an additional step: mixing powdered formula with water that has been boiled and cooled to around 158°F (70°C). Water at this temperature kills Cronobacter, a rare but serious bacterium that can survive in powdered formula. After mixing, let the bottle cool to a safe feeding temperature before offering it to your baby. This step isn’t necessary for older, healthy infants, but it adds meaningful protection for the most vulnerable babies.
Preparing Bottles Safely
Always measure water first, then add the powder. Using the wrong ratio can leave your baby underfed or put strain on their kidneys. Wash your hands before preparing a bottle, and make sure the bottles and nipples are clean and sanitized.
Use water from a safe source. If you’re unsure about your tap water, bottled water is a reliable alternative. In an emergency where bottled water isn’t available, boiling tap water and letting it cool to room temperature before mixing will make it safe. Kendamil dissolves well in room temperature or slightly warm water, so there’s no need to use hot water unless you’re following the extra precaution for high-risk infants described above.