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Decoding those ‘sell by’ dates

What’s the difference between an expiration date and a “sell by” date on a package? Is there any difference between “use by” and “best if used by”? And should you care?

Yes, health experts say. Those dates appear on vitamins, drugs, groceries and other consumer goods for good reason. And by making note of them, you can be sure you’re buying and using wholesome products.

A brief history of time

First, understand the product dating game:

  • “Sell by” is the date by which the retailer should take the product from the shelf.
  • “Use by” is the date after which the product may begin to spoil.
  • “Best if used by” is the date by which a product may begin to lose flavor, consistency or potency.

Of the three, “use by” is the most important. It tells you when perishables—dairy products, meat and baby food—could start developing mold, bacteria or an offensive odor. Use your eyes and nose to check food quality, and remember: When in doubt, throw it out. Don’t risk food poisoning, especially if there’s a baby involved.

That said, milk usually stays fresh for five days and eggs up to three weeks past their “sell by” date when properly refrigerated at 40° F, according to the U.S. Department of Agriculture. Experts suggest using the smell test to double-check.

More dating advice

Several other kinds of products have expiration dates, too.

  • Canned goods in undented containers stay fresh up to five years. Their “best if used by” date suggests they’ll taste better if consumed before then.
  • Soda and beer can taste better if “enjoyed by” a certain date—but they won’t hurt you, regardless of their age.
  • Most drugs work beyond their expiration date—just not as well. To be on the safe side, discard dated, discolored, odd-smelling or decomposed drugs. Keep medicines in a cool, dry place (not the bathroom) out of kids’ reach.
  • Vitamins and supplements can lose potency past their expiration date. Don’t buy them if their package doesn’t carry one.
  • Sundries like contact lens solution and sunscreen also have expiration dates. Observe them—their chemicals degrade and lose effectiveness.