ki4buc, unless you're going by something authoritative you read, I don't believe that short-term freezing would harm most of the meds in pill/tablet/capsule form that we'd carry, like pain killers, decongestants, anti-diarrheals, etc. Ointments/gels, I don't know, depending on the ingredients. Anything injectable should be kept from freezing due to the high water content. I know for a fact that insulin can't be used if it has ever been allowed to freeze, so definitely protect that from freezing.

MDinana is right, this is a topic that hasn't really been researched that well, at least publicly. I don't doubt that the pharma manufacturers themselves have more data on this topic than is generally known. It was only recently that DoD contracted with the FDA to test the condition of its stockpile of expired meds, particularly those stored under adverse conditions (usually excessive heat, like over in the sandbox, not excessive cold). Freezing could also affect the consistency of a product, even after thawing out. Ingredients could separate during freezing that might not mix together again when thawed, although I doubt that it would affect the actual potency of the active ingredients.

There are actually a few different considerations to storing meds outside the recommended temp range:
* Has the medication become less potent?
* Has it become more toxic?
* Has freezing physically compromised the sterility of the product?

The first two things would seem to be more affected by heat than cold. Freezing would likely tend to significantly slow down any sort of degradation or chemical reactions that affect either the potency or toxicity of the meds. Freezing any solutions could certainly affect its packaging as the ice swells in volume, especially any rigid containers, so the last item would certainly be a consideration in the cold but few of us probably carry anything injectable.

Just a random tidbit, but I suppose condensation is another consideration that could affect the long-term stability of meds when you bring them back into warmer environments from the cold. But short term, it's probably not much of a consideration. I mean, how many people keep their meds in their steamy bathroom medicine cabinets for years?

Anyway, I don't have any more definitive knowledge than anyone else, but that's my take on it. ki4buc, if you've got a reference, I'd be interested in reading up on the issue in case I'm actually way off in my opinion here.