What about over the counter medications ?
Like with food, the date doesn't mean that it falls apart the next day. It means that until that date, the manufacturer guarantees that it works and it's safe; after that, not necessarily.
One study actually tested some drugs and found that 15 years after the "use by" date, the medicines still had about 90% of the original amount of drug. But we usually take drugs when we're sick, and we want to be 100% certain that what we're taking is going to work, so it's not a good idea to keep expired drugs.
If it's late at night, I develop an annoying pain, and I notice that the only aspirin/tylenol/advil I have has expired a year ago, I would take it anyway, and the next day I would buy fresh, unexpired pills. For more serious conditions, I wouldn't use the expired pills.
Some drugs should never be used after expiration date: insulin, liquid antibiotics, nitroglycerin. They either become less effective, or turn into something dangerous.
Going through the medicine cabinet and tossing expired pills is part of Pesach cleaning, no?
