When cold sores erupt, they feel anything but cool. The reddish, inflamed skin typically feels hot and blistered. So, it's no wonder that a lot of people recommend a cold compress to knock the sores down a notch.
You may have heard that if you ice a cold sore when it first arrives, you may cut down on the amount of time it hangs around. There doesn't really seem to be much hard science to support that statement.
However, ice packs and cold compresses will provide some temporary relief from the burning, itching and overall unpleasantness of an outbreak. You can simply put some ice cubes in a washcloth or a plastic bag and apply it to the sore for a few minutes several times per day. Provided you're not picking at the sore or playing with it, the ice should help minimize the swelling a bit and will also reduce some of the irritating achiness.
A tasty popsicle will feel good, too, but skip the juice bars. Their acid content may irritate that major irritation even more. Super-cold drinks, such as slushes or smoothies, are another tasty way to provide comfort.