Understanding Medication Expiration Dates
How Long Can You Really Keep Your Meds?
Patients, especially the elderly, often come to appointments with a collection of medications they regularly take. You pick up a hypothetical amlodipine, only to find its expiration date passed a couple of days ago. “Should I throw it away?” the patient asks. Let’s answer that question. We’ll also delve into how long different forms of medications can be stored and why pharmaceuticals indicate short expiration dates on their packaging. Do tablets become useless or even harmful the day after the expiration date? Find out below.
What is the expiration date?
It’s the period during which a medicine remains stable under specific storage conditions (proper temperature, humidity, and protection from sunlight). Manufacturers typically don’t set expiration dates more than 5 years from the start of a specific batch’s production. However, this doesn’t mean medications become ineffective the day after. Nor does it guarantee the opposite.
The storage duration of medications depends on their dosage form:
- Tablets, capsules, and powders can remain stable much longer than indicated (months to even years), but there are exceptions. Nitroglycerin loses effectiveness six months after opening the bottle, while acetylsalicylic acid (aspirin) converts to vinegar. This won’t happen if tablets are protected from moisture in the air.
- Liquid forms deteriorate more quickly. Ear, eye, and nose drops are good for a month after opening, and creams can be used from a month to six months. The rapid expiration of liquid and soft forms is due to bacterial contamination.
- Solutions and suspensions for oral intake have different expiration periods. Antibacterial suspensions are usually viable for 7 to 14 days after being diluted with water, as the active ingredients quickly degrade in water. Other liquids, like paracetamol or ibuprofen suspensions, can be stored for up to 6 months, after which the risk of microbial contamination outweighs the benefits of treatment.
- Injectable forms also degrade over time. Adrenaline is the least stable, and using expired adrenaline could endanger the patient’s life, especially if it fails to counteract anaphylactic shock. However, if using such medication is the only option available, the benefits of its use outweigh the absence of help altogether.
- Insulin should be refrigerated before use and stored at room temperature for no more than a month after opening. During this time, injections remain most effective.
To determine a medication’s expiration date, manufacturers conduct stability studies. They take several packages, store them for 1-3 years in an incubator with constant temperature and humidity conditions, like 25 degrees Celsius and 60% humidity. Afterward, they assess whether the medication has changed its chemical properties or developed toxic impurities.
A date in the format 01.25 means the medication expires on the last day of the month, i.e., January 31st. Manufacturers haven’t studied what happens to the medication after this date, so they don’t assume responsibility or guarantee the safety and effectiveness of expired medications.
Using expired medications is like playing roulette. When prescribing medications past their expiration date, you must ensure that the patient has met all the storage requirements:
- not keeping medications in the bathroom where humidity is high,
- not exposing them to direct sunlight on windowsills,
- not freezing or leaving them in the car, which could expose the medications to drastic temperature changes.