Stop cold sores by icing them? Yes!
Years ago I read that applying ice cubes to an emerging cold sore can stop it dead in its tracks. Nowadays that method of dealing with cold sores (caused by herpes simplex virus) is not mentioned on medical sites. Yet my experience has been that applying ice and holding it on the emerging cold sore absolutely works.
The sore stops developing at the point when the ice is applied. When applied early in development the cold sore never fully emerges, and so the fluid filled blister and weeping stages never occur.
Instead, it will go directly to the scab stage, or even regress to nothing if you get it early enough. The key is to get ice directly on the spot before the sore fully erupts, and to press or hold the ice directly on it for lengthy periods of time - perhaps a total of 30 to 40 minutes (if it's very early in development) up to one hour. For best results, can do a second time in one day. Repeat on day 2 if needed or desired.
Method: Apply an ice cube directly on the area where the cold sore is emerging (but wrap part of it in a paper towel so you can hold it comfortably). Hold it on the spot till the ice cube melts. Then apply a second ice cube to the area until the ice melts. Perhaps even a third (or 4th?) ice cube. Yes, the skin will be a little red afterwards, but that soon goes away.
Big question: Would this method work for everyone? Don't know of any studies looking at this. But some people on Reddit mention successfully stopping cold sores by using ice cubes ("ice the cold sore"). Here and here and here. Some other comments from Redditt:
"I know this sounds crazy but ice will stop a cold sore in its tracks without fail for me! You have to get the ice on there as soon as you feel the tingle though because once it starts to break skin it's much harder to stop. Let an ice cube melt entirely on it, and then another. And maybe a third lol."
"100% works. Anyone not doing this is suffering for no reason. Ice ice ice it!"
"Ice it. Right when you feel it. It stops it from replicating. Stops it right in it's tracks. Won't even get any blisters. It's amazing!"
"Honestly I put ice in a ziploc bag and hold it up to the spot anytime I feel a cold sore coming, usually gets rid of it but only when you do it right when you feel it coming.