How long does expired medicine remain somewhat effective

A pharmacist told me that even when a medicine is past the expiration date, it still maintains a good portion of its strength and effectiveness before it gradually loses the balance of it's potency. But does anyone know how long it takes before a medicine is completely ineffective? Is it months or years? I'm talking about nonprescription medication.

The military conducted an experiment related to prescription drugs. It seems they had a huge amount of left-over stock, most of which had the standard 1-year expiration date. They decided to test the drugs for efficacy and/or changes. Without exception, all of the prescription antibiotics had suffered no deterioration or change in going beyond the expiration date.

However, the FDA still places a 1-year expiration date on all Rx drugs. According to military conducted testing, as long as the drug is kept in dry, dark, cool storage, it is safe for at least 2-years, and beyond that if refrigerated. However, some Rx drugs should not be refrigerated.

With that said, you can probably safely take an antibiotic that has been stored correctly for beyond the one-year expiration date. As long as it has not been exposed to heat or humidity, it should be effective. Never store prescription drugs in the bathroom as the humidity during bathing or showering can effect the efficacy of the drug.

Tetracycline is one Rx drug that carries a warning for toxicity beyond one-year expiration. I would, personally, heed that warning.