Expired cold medicine and other expired over the counter medicine is very safe to take although when the cold medicine or any other over the counter medicine expires it loses it's effectiveness.
That just means that it might take longer for the expired cold medicine to work on your cold virus to make you feel better but the expired cold medicine is not gonna hurt you.
I once took some expired aspirin before and asked my doctor about it and he said it was perfectly safe to take the expired aspirin and that the only problem would be that the medicine that has expired loses it's effectiveness overtime.
So it's safe to take expired cold medicine or expired aspirin or any other expired over the counter medicine but the medicine may not be as effective as fresh medicine or cold medicine would be.