I recently went to Bostonm MA and spent the day walking around the city. I wore the wrong shoes (flip flops) and had quarter-sized blisters on the sole of my feet that evening. I used epsom salt soaks for 3 nights and they disappeared!
The first night I soaked both feet in hot water with about 1.5 cups of epsom salts in it. I did two rounds, soaking for about 20 mins each round.
The following 2 nights, I soaked for the same amount of time with the same amount of epsom salts in the water.
The first morning, I noticed little fluid left in the blisters. These were big blisters and had noticeably shrunken in size.
The second and third mornings, the fluid was gone and the skin started to tighten back up. AMAZING!!