A short list of medicines cannot be treated as probably fine after their date: degraded tetracycline has damaged kidneys, insulin and other biologics fail without a cold chain, mixed liquid antibiotics last only days to a couple of weeks, epinephrine devices weaken with age and heat, and opened nitroglycerin tablets lose strength. For most other drugs, expiry mostly means lower strength, but a medicine that is discoloured, crumbling, cloudy or smells wrong is suspect whatever its class.
Most solid drugs fade slowly, but a few fail by turning harmful or by losing strength quickly, and they need individual handling.
The Exceptions Fail In Different Ways
Some fail by becoming harmful, some by losing strength fast, some by needing a cold chain that no longer exists. Each needs its own caution.
- Tetracycline (the drug itself). Degraded tetracycline has been linked to kidney damage (Fanconi syndrome). This is tied to tetracycline specifically. Doxycycline, a related drug, has not been associated with the same problem in the same way, but that is not a guarantee of potency, and a discoloured or crumbling tablet is suspect either way. Outdated tetracycline should not be used.
- Insulin. Heat and freezing both destroy it. Unopened and kept cold, it is the most reliable. Once in use at room temperature it lasts weeks, not months, and the exact period is set by the manufacturer for each product. Insulin that is clumped, frosted, or cloudy when it should be clear is not usable. Weak insulin means uncontrolled blood sugar, which can be fatal.
- Epinephrine (auto-injectors and vials). It loses strength over time and with heat. Solution that has gone brown or cloudy, or has particles in it, is more degraded. In a life-threatening allergic reaction with no alternative, a degraded device is generally considered better than none. That is a judgement for the moment and does not replace a fresh supply or emergency care.
- Mixed liquid antibiotics. The dry powder keeps far better than the liquid made from it. Once mixed, most liquid antibiotics last only days to a couple of weeks, even if refrigerated, as set out on the product label.
- Nitroglycerin tablets for chest pain. They lose strength once the original container is opened and when moved to other containers. A stale supply may not protect the person relying on it.
- Other liquids, eye drops, creams and injectables. Generally less stable than solids; opened eye drops can become contaminated.
Method: Decide Without A Dose
Step 1: Name the drug. If it is on this list, treat the date and the storage history as decisive.
Step 2: Check how it was kept. For insulin and other biologics, a warm or frozen history means it is unreliable. For epinephrine, check colour and clarity.
Step 3: Prefer a fresh supply where you can get one. A degraded emergency drug is a last resort, not a plan.
Step 4: Look up use and amounts in a reference. This article gives none.
Common Mistakes
- Using the doxycycline reassurance for tetracycline. They are different drugs.
- Trusting a thawed or heat-exposed insulin vial. It may look normal and be useless.
- Keeping an auto-injector as the only protection for someone with severe allergy. A degraded device is a stopgap.
Safety
Some of these fail silently, and some are harmful when degraded
Degraded tetracycline can injure the kidneys; weak insulin leaves diabetes uncontrolled; a weak epinephrine device may not stop a severe allergic reaction. Each of these can kill. When in doubt about identity, history or appearance, do not use the drug, and do not guess an amount.
What’s Next
- Learn next: Critical Drugs to Prioritize — what to carry given these limits
- Combine with: Optimal Storage Conditions — keeping the fragile ones viable