Since 1979, the Food and Drug Administration (FDA) has required pharmaceutical manufacturers to provide expiration dates on all their products. For the majority of drugs sold in the United States, these dates range from 12 to 60 months from the date they are manufactured.
Expiration dates are basically guidelines. Your medications may expire before the expiration date if improperly stored, or they may last well beyond their expiration date, as some studies have shown. While most drugs do not become dangerous when expired, they can still pose a threat to your health. Over time, drugs lose their potency. Using a drug past its expiration date may affect its quality and effectiveness.
Pharmaceutical manufacturers determine a drug’s shelf life, or expiration date, through stability testing. This type of testing ensures that a drug’s potency and integrity are intact over a specific amount of time, which becomes the expiration date. Several factors can influence these dates, including type of active ingredients, storage conditions, preservatives, and the kind of container the drug is stored.
It is important to note that the manufacturers’ expiration dates apply only to the original packaging of the drug, and that once opened these dates no longer apply. Each state has different requirements, but all pharmacists must give the consumer some sort of expiration date, sometimes called a “beyond use” date. This date typically is 6-12 months from the date the drug is dispensed, but may be shorter depending on the type of medication or a manufacturer’s expiration date.
Medications last only as long as their storage conditions are favorable. Drugs can lose their potency long before the expiration date if exposed to oxygen, heat, light, or humidity. In order to maintain their potency, medications should be stored in a place that is dry, cool, and dark. Despite popular practice, this means that your bathroom medicine cabinet should not be used, because its high level of humidity can cause medications to break down and lose their effectiveness. The FDA also recommends keeping medications in their original containers, away from other substances that might be mistaken for it. Specific instructions should always be followed. For example, nitroglycerin should be kept away from light. Your pharmacist may also give you additional storage instructions in the form of a label on the bottle or on a handout.
The accuracy of drug expiration dates has been the subject of much discussion. Since 1987, the FDA has been administering a program called Shelf Life Extension Program (SLEP) for the military. The program tests military stockpiles of drugs to determine stability after the expiration dates have passed. According to the report, of 119 drug products tested, all except for four or five were stable beyond their original expiration dates. Some were extended for as long as ten years beyond their expiration dates.
What does this mean for you? As a consumer, you need to follow expiration dates or beyond use dates very carefully. The impact of the SLEP program was that drugs stored in their original containers in ideal storage conditions can last for long periods of time. But once exposed to the environment, there is no way to predict their effectiveness. Unfortunately, once you bring your medications home from the pharmacy, they are no longer being stored under such controlled conditions.
Drugs vary widely in terms of dosage, form, and stability. Some drugs, like pediatric liquid antibiotics, insulin, and certain injectables will expire more quickly than medications in other forms, such as tablets. The SLEP program found solid dosage forms did better in stability testing than injectables. The program demonstrated that there is a lot of variability even within one product, different lots of the same drug tested differently.
So, remember, your medications will work only as well as they are handled. Taking them safely means storing them properly, reading all specific instructions carefully, and not using them after the recommended amount of time or expiration date.