Expiration explanation: a guide to using products beyond the 'best by' date

June 14, 2011 







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 Patients who have used outdated or contaminated product can get eye infections or worsen a problem they aimed to treat, he said.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.


  • Liquid: Liquids are generally less stable than solid forms of drugs, so err toward abiding by the expiration date, said Ohio State's Weber. Sometimes it's hard to see inside containers to determine if something is off with the liquid, but if it smells funny or looks cloudy or discolored, don't take it. Never swig straight from the bottle, to avoid contamination with bacteria.

  • Solid: While patients should follow expiration dates on prescription drugs, taking expired over-the-counter drugs could just mean they won't be as potent, said Robert Weber, senior director of pharmaceutical services at the Ohio State University Medical Center. There has been some clamoring for a re-evaluation of drug shelf life. The military, upon testing the stability of 122 types of expired drugs, found that many retained 90 percent of their potency five years after their expiration date. But those were unopened and ideally stored; heat or high humidity can shorten life span.


    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.

    Beauty products

    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.)


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