Yes, Epsom Salt works for me when it somes to cold sores. I had one developing on my lip, I popped the lump, then held some epsom salt on it twice that day and by the next day the area was flat and healed.
No idea where I ever got the idea to try this, but it has worked every time for me. When I get a cold sore, I put a crystal of epsom salt on it. It stings for a bit, but within a short period of time the pain is down, a few hours I know its already on the mend, and the next day its usually about 1/2 to 2/3 cleared up. It only needs to be done once.