Unopened infant formula typically lasts 12 to 18 months from the date of manufacture, depending on the type and brand. Every container of infant formula sold in the United States is required by the FDA to carry a “use by” date, and that date is the single most reliable guide to how long your specific container will last.
What the “Use By” Date Actually Means
Unlike the vague “best by” labels on many grocery items, the “use by” date on infant formula carries real regulatory weight. The FDA requires manufacturers to put this date on every container, and it represents a guarantee: until that date, the formula will contain no less than the amount of each nutrient listed on the label and will otherwise meet quality standards. Manufacturers determine this date through testing, so it reflects the point at which nutrient levels can no longer be assured.
This distinction matters because infant formula is often a baby’s sole source of nutrition. A jar of peanut butter that’s a month past its best-by date might taste slightly stale but is nutritionally fine. Formula doesn’t get the same pass. If key vitamins have degraded below what’s printed on the label, your baby may not be getting what they need.
Shelf Life by Formula Type
Powdered formula generally has the longest shelf life among the three main types. Most cans are stamped with a use-by date roughly 12 to 18 months from manufacture. The low moisture content keeps it stable, but it is not sterile, which has implications for safety (more on that below).
Liquid concentrate and ready-to-feed formula tend to have shorter shelf lives, often closer to 12 months or less. Because they contain water, they’re more susceptible to changes over time, even while sealed. Ready-to-feed formula is sterile inside its sealed container, which makes it the safest option for newborns and immunocompromised infants, but that sterility only holds as long as the seal is intact and the container is undamaged.
Why Nutrients Break Down Over Time
Vitamin C is one of the first nutrients to degrade in stored formula. It oxidizes in the presence of oxygen and breaks down further into compounds that no longer offer any nutritional benefit. The rate of this breakdown depends on temperature, light exposure, and time. Research on vitamin C loss in similar infant food products shows that degradation follows a steady, predictable pattern: the longer the product sits, the more vitamin C is lost, with retention staying above 68% only under refrigerated conditions. Since unopened powdered formula is stored at room temperature, losses accumulate faster than they would in a fridge.
Fat-soluble vitamins and the fats themselves also change over time. Lipids can oxidize, producing off-flavors and reducing nutritional value. These changes are why the use-by date exists: it marks the window in which the manufacturer can still guarantee the label’s nutrient claims hold true.
Bacteria Can Survive in Sealed Powder
A common assumption is that sealed, dry formula is essentially sterile. It’s not. Powdered infant formula can harbor bacteria including Cronobacter sakazakii, Salmonella, and Listeria. Research published in the Journal of Food Protection found that all of these organisms survived in powdered formula for up to 360 days at room temperature (25°C), persisting for at least 90 days without any significant drop in population regardless of humidity conditions.
This doesn’t mean every can of formula is contaminated. Contamination events are rare. But it does mean that powdered formula is not a sterile product, and time alone won’t eliminate bacteria that may be present. Using formula past its use-by date extends the window during which any low-level contamination could matter, especially for premature infants or babies with weakened immune systems.
How to Store Unopened Formula
Keep unopened containers in a cool, dry place. A pantry or kitchen cabinet away from the stove, dishwasher, or direct sunlight is ideal. Heat and humidity accelerate both nutrient loss and any potential bacterial activity. Avoid storing formula in a garage, car trunk, or anywhere temperatures fluctuate significantly.
Don’t stockpile more formula than you’ll use before the earliest use-by date in your supply. It’s tempting to buy in bulk when a sale hits, but formula sitting in a closet for months is formula losing nutritional potency. Rotate your stock so you’re always reaching for the can with the nearest use-by date first.
How to Check a Container Before Using It
Before opening any container of formula, inspect it carefully. Do not use formula in a can or bottle that is dented, bulging, leaking, or rusty. A bulging container can signal bacterial contamination and gas production inside the seal. Rust can compromise the integrity of the metal, allowing air or microorganisms in. Leaking containers have already lost their sealed environment.
The use-by date and lot number are typically found on the top or bottom of the can, printed as embossed (raised) text. Below the use-by date, you’ll find a product identifier and lot number. If a recall is ever issued, these codes are what you’ll need to check whether your specific container is affected. It’s worth glancing at them when you buy a new batch and keeping the information accessible.
What If the Formula Is Past Its Date
Using formula past its printed use-by date is not recommended. The concern isn’t that the formula becomes toxic overnight. It’s a gradual issue on two fronts: nutrient levels may have dropped below what the label promises, and the margin of safety around any potential contamination narrows the longer the product sits. For a food that may be your baby’s only source of nutrition, those margins matter.
If you find yourself with expired formula and no alternative, contacting your pediatrician is a reasonable step. In an emergency or supply shortage, a can that’s a few days past its date is a different situation than one that expired six months ago. But under normal circumstances, replacing expired formula is the straightforward move.