Does the expiration date on a bottle of a medication mean anything? If a bottle of Tylenol, for example, says something like ‘Do not use after June 1998,’ and it is August 2002, should you take the Tylenol? Should you discard it? Can you get hurt if you take it? Will it simply have lost its potency and do you no good?

In other words, are drug manufacturers being honest with us when they put an expiration date on their medications, or is the practice of dating just another drug industry scam, to get us to buy new medications when the old ones that purportedly have ‘expired’ are still perfectly good?

These are the pressing questions I investigated after my mother-in-law recently said to me, ‘It doesn’t mean anything,’ when I pointed out that the Tylenol she was about to take had ‘expired’ 4 years and a few months ago. I was a bit mocking in my pronouncement — feeling superior that I had noticed the chemical corpse in her cabinet — but she was equally adamant in her reply, and is generally very sage about medical issues.

So I gave her a glass of water with the purportedly ‘dead’ drug, of which […]