This is how long the medical drug remains active, safe & effective.

Wall Street Journal Europe, March 29, 2000, had an article by staff reporter Laurie P. Cohen headlined "Many Medicines Prove Potent Long Past Their Expiration Dates." 90% of the drugs that the U.S. military tested in their warehouses were safe and effective far past the "expiration date." Drug companies indignantly deny that they simply want you to throw out good medicine and buy more, but it is quite profitable for them if you do. Some drugs--like antibiotics--you shouldn't have left-over in the first place, and shouldn't self-medicate with in the second place. Nitroglycerine, tetracycline, insulin and liquid antibiotics do degenerate--throw them out. Medicine also degenerates fastest in your medicine cabinet because of shower's heat and humidity. With the vast majority of medicine, though, you can try it if you're sure your disease is the same, and if it works, it's good. The expiry date is usually just a guarantee--and we all know that most things don't wear out until long after the guarantee expires. So don't let the date scare you. Most pure, dry chemicals are quite stable and don't turn to something harmful if kept in a cool, dry place.