As long as it's properly kept, it's not unsafe to use. It won't spoil like milk would. There's a certain length of time that the drug will hold where it's dosed at before it gradually....VERY gradually begins to taper down. It has to be considered expired now because it might longer be holding at the dose on the bottle so a doctor can no longer prescribe it, not knowing what dose is actually in there, even though it's probably still very close if not the same...FDA plays that role. I would say a better analogy would be a fully charged battery that is stored away. It will gradually lose it's power but can still be a good functioning battery. If your told a battery will only hold a FULL charge when not being used for say...3 days, would you throw it away 1 wk later, simply because it may only be at 97% now, or would you still use it?