Since I've been massaging my feet regularly with Hirschtalg* I've hardly had any blisters to speak of and certainly not any mega-blisters.
*It's made from deer fat and comes in a green tube. Don't mistake it for toothpaste...
. There is a variety in a red tube but it's not as good.
manufacturer: Rohde
ingredients: deer fat, beeswax, chlorophyl, vitamin E
advantages: heals blisters and protects like a second skin
ps- I have no connection to the firm making this excellent product. I am merely a satisfied customer.