While going through the cabinet in my bathroom tonight, I came across some things I haven’t used in a long time that have expiration dates that have passed. My question is what exactly happens with these products after expiring? Do they become ineffective or harmful? Here’s the products and expirations: Aspercreme 6-09, saline nasal spray 6-08, Chap Stick 4-09, Neosporin 2-08.
A law was passed in 1979 requiring manufacturers to stamp an expiration date on medications. This is generally the date that the manufacturers can guarantee (or are required to) the potency and safety of the drug.
Most, if not all drugs will remain safe to take and use, but may be less effective (a possible exception is tetracycline which may become unsafe). This cite says it better than I can:
In short, your products are probably still safe to use. I would however throw out the nasal spray if it has been used due only to the possible contamination of the nozzle…but that is a judgment call.
An expiration date on medication signifies when the manufacturer can verify that the medication is still safe and effective, with at least… (wow, been awhile since that class)… even 95% or 99% of the active ingredient remaining, and there are no toxic metabolites. There are two ways they can get an expiration date, even by locking up a sample for however long and then testing it, or by what’s called Advanced Stability Testing.
Advanced Stability Testing is where they take a sample, then put it through different temperatures, pressures, etc to artificially age it. According to FDA rules, they can only certify a maximum of three years by using Advanced Stability Testing, so this is the date most drugs are assigned. And since there is not normally an incentive to retest a physical sample after the drug has been on the market for over three years, they normally keep this expiration date indefinably.
Most drugs are probably fine after the expiration date, as long as it is unopened and has been properally stored (75 degree F, low humidity, etc). However, under most real life storage conditions (in the bathroom, wildly changing temperature and humidity), I wouldn’t trust the drug, and would probably just throw it away.
While Advanced/Accelerated stability testing can give the first expiry range and storage conditions for a drug product, it is a legal requirement for companies to continue to test on-going stability of manufacturing lots throughout the commercial lifetime of the drug. That means that some samples from a certain amount of lots (batches) per year are stored at their recommended conditions and tested at certain time points for the next few years (2-3, depending on the results of the accelerated testing, typically). So for a standard set of pills usually kept at room temperature, the manufacturing company is verifying those pills at 25C/Ambient RH every six months or so to ensure that they are still within specifications.
As a bit of an aside - household bathrooms are a terrible place to store drugs, since the humidity is generally much higher and much more variable than the stability conditions under which most drugs were approved. Kitchen/bedroom cabinets are a better choice for most drug products.
As for what can happen: that depends on so many factors, there is no one answer because it will vary by the drug and the storage conditions. Generally, any or all of the following can happen;
Nothing. The drug remains as safe as the day it was made. There is, however, no drug in the world for which laboratory data exists to support this, because there is no reason (legal, financial, scientific curiosity) for companies to test drug lots indefinitely. 2-3 years of stability is enough - go buy another bottle already!
The active ingredient has degraded into harmless substances. The effectiveness of the drug is reduced, because you now have 95 or 80 or 7% of the original drug potency, and so taking the drug would result in undermedicating the symptoms (which can end up in overmedication if the patient feels it isn’t working well enough and doubles the dose…). Harmless degradation products have no appreciable effects on the patient. Again, there is no drug in the world for which laboratory data exists to support this for the same reasons as above. You’ve had 2 or 3 years, go buy another bottle already
The active ingredient has degraded into harmful substances. In addition to the lower potency from whatever is left, you now have stuff in there that can harm the patient; exacerbated side effects, toxic substances, mutagens, who knows? Well, the pharma company knows, because they’ve tested for this and know that the drug breaks down in time into substance A and B and they are harmful, and so stability testing has shown that they last a minimum 2-3 years before A and B reach 0.X%, which is the minimum cut-off due to the known effects of A and B, and so there’s your expiry date. There is no incentive to test to see how far the harmful stuff builds up after 4, 5, 15, 99 years. Go buy another bottle already (do I need the smilie?)
The active ingredient has completely disappeared, so you have zero effect on the symptoms you are trying to treat, and the degradation products may or may not be harmful, and…you get the idea.
The main point is that while we can speculate that most drugs are probably still safe, there is no data whatsoever to support that assertion. Clearly it’s not a time bomb - it’s still good a day later, probably a month later, maybe even 6 months later, but at some point it is no longer safe. No one has studied it, tested it, verified it and so you are taking a chance if you take medication a year or two out of date. That chance can be trivial - the drug can simply have no effect on your cold/headache/manic depression - or it could be serious - the degradation product could be another drug entirely, which can severely affect your health.