What Is an Expiration Date?

An expiration date is a date after which a consumable product such as food or medicine should not be used because it may be spoiled, damaged, or ineffective. The term expiration date also refers to the date that a drug patent expires.

Understanding Expiration Dates

Expiration dates are especially important for medications because they offer the only indication about whether the product is still safe to use. Food items, on the other hand, often look or smell bad when they have passed their "best-buy" dates. Because using expired medical products may potentially harm our health, in the late 1970s the United States Food and Drug Administration (FDA) mandated that all prescription and over-the-counter (OTC) medical products contain an expiration date. Expiration dates for medicines are often marked “EXP” and are printed on the label or stamped onto the medicine bottle or box.

Certain medications can be fatal to children or pets if they ingest even the smallest amount; these should be flushed down the sink or toilet once they pass their expiration date.

Why Using Expired Medicines Can Be Risky

It is especially important to adhere to the expiration dates of pharmaceuticals. Because their chemical composition can change over time, expired medicines risk becoming less potent, less effective, and even harmful. For example, an expired medication might not be able to control the underlying condition as well as a medication that has not reached its expiration date, so using it could have serious consequences.

In some cases, the FDA may extend the expiration date of a drug if there is a shortage of it. The extended expiration date is based on stability data for the medication that has been reviewed by the FDA.

Discarding Expired Medications

Instead of dumping them in the trash, you should discard expired medications properly. If there are no disposal instructions on the drug's packaging, you should check for drug take-back programs in your state or municipality.

In the absence of specific instructions or take-back programs, U.S. federal guidelines recommend disposing of expired or unwanted medicines by putting them in a bag or container and mixing them with coffee grounds or kitty litter. Some medications should be flushed.

Expiration Dates for Food

With food, however, expiration dates are a somewhat different story. Food manufacturers provide dating to help consumers and retailers decide when food is at its best quality. Except for infant formula, dates are not an indicator of a product’s safety and they are not required by federal law. A food product label may contain two types of dates:

Open dating is a calendar date applied to a food product by the manufacturer or retailer. The calendar date tells consumers the estimated time for which the product will be of the best quality, and it helps stores to decide how long to display the product for sale.

is a calendar date applied to a food product by the manufacturer or retailer. The calendar date tells consumers the estimated time for which the product will be of the best quality, and it helps stores to decide how long to display the product for sale. Closed dating is a code that consists of letters and/or numbers; it is applied by manufacturers to identify the date and time that they produced the item.

Key Takeaways Using expired medical products may potentially harm our health.

In the late-1970s, the FDA mandated that all prescription and OTC medical products contain an expiration date on their labels.

With food—except for infant formula—expiration dates are not required by law, nor do they indicate a product’s safety; they refer to the product's freshness and best quality.

The FSIS: Watchdog for Our Meat, Poultry, and Eggs

The Food Safety and Inspection Service (FSIS), an agency of the United States Department of Agriculture (USDA), is the public health regulatory agency responsible for ensuring that America's commercial supply of meat, poultry, and eggs is safe, wholesome, and correctly labeled and packaged. The FSIS's mission statement reads: "Protecting the public’s health by ensuring the safety of meat, poultry, and processed egg products."

For these products, manufacturers may assign expiration dates voluntarily if they are labeled in a manner that is truthful and not misleading, and which complies with FSIS regulations. To comply, a calendar date must express both the month and day of the month. Shelf-stable and frozen products also must display the year. Further, immediately adjacent to the date must be a phrase explaining the meaning of that date—such as, "Best if Used By."

Date-Labeling Phrases for Food Products

There are no uniform or universally accepted descriptions used on food labels for open dating in the United States. As a result, producers use a variety of phrases on their labels to describe quality dates:

Best if used by/before: This date indicates when a product will be of best flavor or quality; it does not indicate safety or when to purchase.

This date indicates when a product will be of best flavor or quality; it does not indicate safety or when to purchase. Sell-by: A sell-by date indicates to the store how long to display the product for sale for inventory management; it is not a safety date.

A sell-by date indicates to the store how long to display the product for sale for inventory management; it is not a safety date. Use-by: This is the last date recommended for the using the product while at its peak quality; it is not a safety date except when used on infant formula.

This is the last date recommended for the using the product while at its peak quality; it is not a safety date except when used on infant formula. Freeze-by: This date indicates when a product should be frozen to maintain its best quality; it does not indicate safety or when to purchase.

Ways That Food Manufacturers Decide Quality Dates

When determining the date by which a product will be of the best quality, producers and retailers consider factors like the length of time and the temperature at which a food is stored while it's in distribution, and before being offered for sale. Other factors, such as the particular characteristics of the food, and its type of packaging will affect how long a product will be of optimum quality.

Although it's true that the quality of perishable products may deteriorate after the labeled date passes, such products should still be safe if they're handled properly. Consumers must evaluate the quality of a product—by looking, smelling, tasting, and touching—prior to consuming it to see if the item shows signs of spoilage.

Expiration Dates for Prescription Drug Patents

The U.S. Patent and Trademark Office awards medical patents to pharma companies when a new brand-name drug is released to the market. The patent protects the drugmaker from having its drug copied by competitors for a certain time, typically 20 years. The patent exclusivity for orphan drugs lasts for seven years, and a patent for a new chemical lasts for five years.

The Orange Book—a list of drugs that the FDA has approved as both safe and effective—cites the patents for new drugs, along with their expiration dates. Under the Hatch-Waxman Act, for a generic drug manufacturer to win approval for a drug, the manufacturer must certify that it will not launch its generic product until after the original drug's patent has expired; unless the patent is found to be invalid or unenforceable, or if the generic product will not infringe upon the listed patent.