Roche's data on tamiflu is pretty clear- the senspension is only good good for about ten days and MUST refrigerated. The tablets require storage at 25C (77F) with limited variation, and that it shouldn't go below 15C (60F) or above 30C (89F). I haven't found out what happens if it gets too warm, but I doubt that it's good for the effectiveness of the drug.

Every so often, you used to hear horror storied about improperly stored meds that had soured and gone toxic. I've never found any first or second hand accounts of this, it's always been "friend of a buddy" war stories. But they are worth keeping in mind.

That's part of why I hammer people who stash meds. They don't have a suitable facilty, much less the training, as a rule.