How long can you use medication after the expiration date?

It's late and someone in your house has a headache, a stuffy nose, or – oh no, was that the sound of retching? You sift through the clutter of medications in your home, quietly pumping your fist in the air when the bottle of Tylenol or Pepto-Bismol finds your hand.

Only then do you notice the expiration date: it was last month, last year, last decade. You realize that you don't know what this actually means – whether the drug you have in your hand is dangerous or just ineffective, and whether you would cause more harm by using it or withholding it.

For many, medication expiration dates are a source of fear and doubt. Whether it's an over-the-counter fever medicine or an important prescription heart medication, knowing how to assess the risk of taking it or not taking it can save you a lot of worry. Here's what you need to know about medication aging.

Expiration dates are somewhat arbitrary

The U.S. Food and Drug Administration only began requiring drug manufacturers to include an expiration date on medications in 1979. However, it gave no instructions to companies on how to set these dates. Most companies have not opted for the costly work of methodically testing each drug during development to determine the exact age at which it begins to degrade. Instead, most simply chose a date a few years later, tested the drug's effectiveness at that point, and called it the expiration date when it was still as good as new.

That is, the expiration date of medicines is not so much an “expiry date” as it is a “good-before” date. For most drugs, these dates are about three years from the day they were manufactured, says Lee Cantrell, a pharmacist and toxicologist who also heads the San Diego division of the California Poison Control System.

However, many medications retain much of their effectiveness for much longer than three years. In 2012, Cantrell and several of his colleagues tested a number of drugs (including acetaminophen, the sedative phenobarbital, and the opioid hydrocodone) that were decades past their expiration dates and found that 86 percent of them still had the intended concentrations of their active ingredients . A few years later, a group of German researchers conducted a similar study with similar results.

One of the German researchers, Ulrike Holzgrabe, a pharmaceutical chemist at the University of Würzburg, told me these results suggest that pharmaceutical companies should set expiration dates more strictly. “After a drug is approved, companies should store the drugs for an additional 10 years” and test them annually for stability, she said.

According to Cantrell, there is an obvious disincentive for manufacturers here: Proving that certain products have a much longer shelf life than we think would mean they need to be restocked less often, which would lead to a decline in sales. Some manufacturers may actually have conducted studies showing that their products last well past their expiration date—but “there's no way they would ever release that data—it's just not in their interest,” Cantrell says.

Replacing drugs that are still effective is wasteful and expensive. To better utilize their drug supplies, federal agencies that stockpile drugs – such as the military and the Department of Veterans Affairs – asked the FDA in the 1980s to extend the official shelf life of several drugs. To do just that, the agency developed the Shelf Life Extension Program by batch testing key medications that are nearing their expiration date.

However, these extensions only occur in individual cases – and only for pharmacies that are operated by state institutions. Although the expiry date does not accurately reflect the actual lifespan of a drug, the system we currently have does not take this into account.

Drugs change as you age, but not in the way you might fear

Part of the problem with drug expiration dates is that it is difficult to tell with the naked eye whether most drugs are past their prime. “A drug is not yogurt, a piece of meat or a strawberry,” says Holzgrabe. Nevertheless, experts have a sense of what invisible changes in medications are likely and unlikely to occur after a certain period of time.

First, drugs typically do not turn into poison as we age. “I don't know of any medications that become toxic once they're past their expiration date,” Cantrell says. This means that you usually don't have to worry about an expired medication making you sick. However, because some medications become less effective over time, expired medications can cause harm because they don't work the way you expect.

Changes in the integrity of the inactive ingredients of some medications may also occur over time. These are drug additives that bring the active ingredients of drugs to where they are needed or make them palatable to the consumer. For example, a skin cream used to treat eczema might peel off or change consistency over time, or a suppository containing fever medication might melt. Conversely, liquid formulations can slowly condense as the water and alcohols they contain evaporate. That means a shot from that older bottle of NyQuil could theoretically be stronger than it should be.

Sometimes, over time, the delivery system of a medication may become ineffective and you will not be able to access the medication it contains. This is the same concept that renders an old can of hairspray unusable, even if there is still a lot of product left in it: medications that rely on propellants — like itch-fighting sprays or the albuterol rescue inhalers that people use to control asthma symptoms – are often used useless if their containers are too old.

Not only do the years change the effectiveness of our medications, the way they are stored can also have an influence. Exposure to sunlight, heat and moisture causes drugs to break down more quickly. These exposures can also promote microbial overgrowth, even with unexpired medications. Although this risk is more related to unsafe medication storage than the age of a medication, it is worth being aware of. This is especially true for medications that are intended to be sterile, such as eye drops, as contamination can cause permanent eye damage to people using these products.

How to deal with household medicines to minimize worries

To prevent medications from losing their effectiveness prematurely and reduce the chance of being inundated with germs, Holzgrabe recommends storing them in the bedroom—not the bathroom or kitchen, where they're more likely to be exposed to heat and humidity.

The safest approach is to keep only unexpired medications in your home – especially when it comes to life-saving medications like antibiotics, blood thinners, EpiPens, asthma rescue inhalers, insulin, and the like. The FDA recommends consumers regularly take inventory of their supplies and throw away expired medications. The agency also provides recommendations for the safe disposal of various types of medications.

However, if you find yourself in an emergency situation where you only have an expired version of a life-saving medication and can't immediately get a new supply, use the medication you have – as long as it doesn't delay taking the sick person's emergency care . “If someone called me and asked me and said, 'This is all I have and I'm having trouble breathing and stuff,' I would say, 'Use it,'” Cantrell says.

The truth is, experts say they often use expired over-the-counter medications at home in non-emergency situations — for example, when they have a child with a cold. However, they cannot recommend it to others; More rigorous drug testing simply needs to be done before this kind of general advice can be given.

Although medications may have a longer shelf life than stated on the packaging, it should not be up to consumers to guess which ones might still be effective. Instead, manufacturers should examine each newly approved drug to determine its actual expiration date by storing it annually and testing its stability, Holzgrabe says. Stricter regulation of the pharmaceutical industry would help, she says: “The law needs to be changed so that we don't throw away so many drugs that are still okay.”