The medical staff at American Partisan have a good post up about medication, how long it stays effective on the shelf, and what you might want to have on hand in case of emergencies. Ditch Medicine: Medications.
Most oral medications are given a rather arbitrary expiration date which may vary depending on the manufacture date, sell date, or type of medicine and concern over poor storage environments at home. Some manufacturers of medications indicate their desire to have their medicines expire, because they want patients to have up to date information about the medicine on the newer packaging.
The Pentagon shelf-life extension program has shown that many medications are safe and completely effective many years after the expiration date listed on the product, especially if stored in a favorable environment. This is also extensively supported with numerous articles found by looking up “Myth of Medication Expirations” on the internet.
Many drugs stored under favorable conditions retain over 90% of their potency for at least five years beyond the expiration date on the label, and sometimes much much longer. Ciprofloxacin, for instance, was found to be completely safe and effective when tested nearly 10 years after the expiration date. Some medications appear to be more stable and therefore retain a greater amount of potency after expiration; these seem to include Cipro, Flagyl, lidocaine, atropine and possibly the penicillins.
Some medications are more unstable and do have an expiration such as insulin, nitroglycerin, aspirin and water purification tablets. A disputed article in one publication suggests expired Tetracycline may have caused toxicity in one patient (personally I don’t believe it since I am sure millions of doses of expired tetracycline have been used in 3rd world countries with no other reported complications; also, that old formulation of tetracycline is no longer available anyway, so I would be willing to expired tetracycline if I needed the medication). I am not aware of any other expired antibiotics having this risk.
Preferred storage environments would be cool, dark, and dry. Blister packaged medications might be preferable because they are kept dry and are waterproof but have the disadvantage of being slightly more bulky. Tablets are typically more stable and therefore have longer storage life than do elixirs/liquids. Many medications may be ordered over the internet as pet medications. Quality controls for pet medications seem good and I would be willing to use them on myself in an emergency.
The below is a list of commonly encountered medications that you might want to know about, and I would recommend finding a drug dose reference book from a bookstore or the internet; sometimes you can find them very inexpensively from book sections at Christian/Salvation Army stores…