It is a common thought that once medication is expired, it will not hurt you, but just be less potent. While this can certainly be the case, there are plenty of examples where taking a medicaiton that has lost potency, or is not as effective, can be detrimental to your health.
One such example is for antibiotics. Taking antibiotics that have reduced strength can lead to antibiotic resistance and lead to inadequate treatment of your infection. The longer an infection is allowed to go on, the greater the risk of serious consequences.
Another such example is with pain medications. Taking pain medication that has reduced efficacy can lead you to taking it incorrectly (overdose). This can lead to increased risk of potentially serious adverse events such as respiratory depression.
As is can be difficult or near impossible to tell whether or not your expired drug has lost potency, it is recommended to discard of it and see your doctor for a new prescription.
Do Medications Go "Bad"?
Most medicaiton do not degrade to the point where they are responsible for causing adverse effects. There were reports in the 1960's of expired tetracycline causing Fanconi Syndrome, a type of kidney disorder, but there is skepticism about this now. The form of tetracycline in the reports is not used today anyway. Nevertheless, you may hear from your pharmacist or doctor that it dangerous to take outdated tetracycline.
Other medications, like outdated aspirin, do degrade enough to physically notice. One of the byproducts of aspirin degredation is acetic acid, which is why that old bottle of aspirin you have may smell like vinegar.
On the whole though, most expired medications are not thought to be physically harmful. The most concern lies with the fact that expired medication may not be providing the needed dose of active ingredient, leading to therapeutic failure, which in itself can be extremely serious.
Why Are Expiration Dates Used For Prescription Medicine?
The expiration date for any given prescription medication is determined by multiple factors but, most importantly, refers to how long the manufacturer is willing to guarantee that the product meets the labeled standards of potency and purity.
Most medication is listed with an expiration date of 2-3 years from the time of manufacture, which typically correlates with the time period for which the manufacturer performed stability testing. After this expiration date, it doesn’t necessarily mean that the medication “goes bad” as discussed above, it just means that the manufacturer is sure that the medication will still retain the listed potency and purity when stored at proper conditions.
Expiration Date Vs. Beyond Use Date
When a pharmacy dispenses you a medication, it must be labeled with an expiration date or a beyond use date. The beyond use date that is listed depends on the product being dispensed and takes into account how long a drug is stable after being dispensed.
In most cases, the beyond use date will be shorter than the manufacturer expiration date as the beyond use date specifically refers to an expiration time after dispensing or repackaging a medication. The state in which you are located has laws to determine the beyond-use date for most dispensed products.
Most commonly, and as a general rule of thumb the beyond-use date (commonly listed as the expiration date on the prescription bottle) will be one year, or the manufacturer listed expiration date, whichever is sooner.