What occurs to medications when they pass their expiration date?

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I have tons of old medications from prescriptions that I never finished, or giant Costco bottles of Advil etc. A doctor that I know told me that the expiration dates mean nothing and that they are just Big Pharma’s way to insert some planned obsolescence into their products.

Is this true? If not, what actually happens to the medications after their expiration dates?

In: Chemistry

8 Answers

Anonymous 0 Comments

Overtime, various chemical effects will change the chemicals in medications into other chemicals, which may have various effects: changing flavor, making the medication ineffective, making the medication stronger, or even making the medication toxic.

There are a number of causes of these, a few of the most common are:
– Oxygen in the air doesn’t like to remain free oxygen, and may combine with other chemicals. As a side note, this is why fat goes rancid.
– UV light, especially from the sun, tends to cause chemicals to break apart.
– Heat will cause chemicals to break apart or combine in a large number of ways.
– Cold will cause chemicals to change form, such as freezing, which can cause various damage.
– Moisture in the air will tend to absorb into chemicals, changing their behavior.
– Microbes might start to grow in or on the medication, which is more likely for wet medicines.

The expiration date is the time window the manufacturer is willing to guarantee these effects remain minimal. The FDA requires companies provide *some* timeline for safety reasons.

That said, the US government also keeps a [drug stockpile](https://aspr.hhs.gov/SNS/Pages/Sustaining-the-Stockpile.aspx), and regularly tests medications in it for safety and effectiveness. It is very common for drugs to remain good for years after their official expiration date, and some even for decades.

Naturally, that stockpile is kept under ideal conditions, and typical home storage may not get the same results. When the stockpile shows medications remain good much longer than their expiration date, the FDA will also do additional review to see if that holds under more normal storage, and may tell manufacturers to increase the expiration period.

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