CHICAGO -- There are telltale signs that a product has gone bad. Moldy bread. Clumpy milk. The layer of fur blanketing the cream cheese. But what about the toothpaste sitting in your pantry for years after a zealous bulk purchase? Or those condoms waiting optimistically in your nightstand for longer than you wish you recall?
Many such products carry expiration dates, but thrifty shoppers often wonder if they really must toss dated items that still "seem" perfectly fine. After all, how can headache medicine stop working from one month to the next? And why should you believe the expiration date on one lotion when another doesn't carry one at all?
The Food and Drug Administration requires that expiration dates be printed on all prescription and over-the-counter drugs, but not on cosmetics -- unless the cosmetics are also considered drugs, such as toothpaste with fluoride, anything with sunscreen, anti-dandruff shampoo and antiperspirant. But even then, over-the-counter drugs without dose limitations don't have to carry expiration dates if tests have proven they're stable for at least three years, which is why one sunscreen may have a date while another won't.
Expiration doesn't necessarily mean the product turns putrid or ineffective once the date passes. Manufacturers set expiration by choosing a date and conducting stability tests to ensure the product will still be good at that time.
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Expiration dates tend to be conservative to account for a wide range of storage conditions and consumer handling, said Dr. John Bailey, chief scientist with the Personal Care Products Council, an industry trade group. But for some products there can be a cushion. Here's a guide to products that commonly carry expiration dates.
Sterility is the greatest concern. The preservatives used to prevent microbial overgrowth become less effective over time, putting the solution at risk of contamination, said Dr. Thomas Steinemann, ophthalmology professor at Case Western Reserve University. Patients who have used outdated or contaminated product can get eye infections or worsen a problem they aimed to treat, he said. Also, especially once a bottle has been opened, the water starts to evaporate, leaving behind a greater concentration of salt, said ophthalmologist Elmer Tu.
The ingredients that absorb UV light and prevent it from reaching your skin can change or degrade with time and extreme temperature, diminishing the effectiveness of the sunscreen, said Dr. John Bailey, chief scientist with the Personal Care Products Council. If the product still looks, smells and feels right, you can probably use it for a year past the expiration if you're willing to take the risk (that is, if you tolerate the sun well), Bailey said. But if you're fair-skinned or burn easily, it's best to abide by the date.
The greatest concern is the reduction in the concentration of fluoride, which is key to cavity prevention, said Frank Lippert, a researcher at Indiana University's Oral Health Research Institute. Anti-tartar and whitening agents also can degrade, making the product less effective. Toothpastes with chemicals such as triclosan, which fights gingivitis, have an even shorter shelf life because that chemical can leach into the packaging material over time, cutting effectiveness. Also, disappearing flavor and the process of syneresis (when water leaves the gel and makes the tube hard to squeeze), make old toothpaste unpleasant.
For cosmetics with active ingredients, such as acne-fighting or anti-aging products, abide by the expiration date because the low concentrations of active ingredients can degrade quickly, said San Francisco dermatologist Richard Glogau. Other cosmetics that don't require expiration dates sometimes still carry them, often in the form of PAO (period after opening), a symbol of an open jar that suggests how many months you should keep the product after opening it. The biggest risk is microbial growth. If it doesn't look or smell right, it's time to dump, said Bailey.
Because the latex in condoms degrades over time, becoming brittle and more prone to breakage, the FDA requires they carry an expiration date, up to five years from the date of packaging, established by testing to ensure their integrity. Storing condoms for prolonged periods in a hot environment, such as a windowsill or glove compartment (a wallet is usually OK), can speed up deterioration, while storing in a cool, dry place could make them usable past the expiration date, said Dr. John Santelli, professor of clinical population and public health at Columbia University's Mailman School of Public Health.
There's no reason not to use an old battery unless there's visible damage to the can, said Kurt Iverson, spokesman for Duracell, which prints a seven-year shelf life for its alkaline batteries as a guarantee rather than an expiration. The metals oxidize as they age, and there can be a small amount of self-discharge from batteries as they sit for long periods unused, but the only consequence is that an older battery might have a shorter life, Iverson said. (Tip: Don't store batteries in the refrigerator or freezer; room temperature is best for quality and life span.)