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I have been wondering for some time whether several drugs really have an expiration date.

Let's narrow the scope and think about only "common" drugs, e.g NSAIDs, antibiotics etc. For example, would antibiotics in the pills get deactivated or decomposed?

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Question sounds appropriate. I suggest reading… – bobthejoe Jul 30 '12 at 8:32
Could you clarify whether you're interested in antibiotics, activated carbon or about expiration dates in general? – Mad Scientist Jul 30 '12 at 9:08
@bobthejoe: thanks that link really helped, but I guess it would be good to have something similar written here as an answer just to gather more knowledge on this site. – zeller Jul 30 '12 at 9:52
It really does depend on the drug in question – Rory M Jul 30 '12 at 14:10
@RoryM: ok then, you're suggesting that the question is too wide and can't be answered exhaustively. Then I'll reduce the scope. – zeller Jul 30 '12 at 15:43
up vote 3 down vote accepted

Drugs do not have to degrade after their expiration date and passing the expiration date has more than one possible meaning.

First of all chemical compounds vary in their susceptibility to breakdown over time. If they are kept away from oxygen, high temperatures (or kept in very low temperatures), and they are of a robust chemical nature, they might be stored for much longer than their expiration date and remain just as strong.

Over time, pharma compounds will chemically break down and lose their potency. In many cases, you will find that they simply don't do anything when you take them. This link cites a study that many drugs can retain their potency 15 years after they are made.

There are important exceptions. Two examples are tetracycline and acetaminophen (tylenol) whose breakdown products can increase the tendency for these drugs to induce liver damage.

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