|I realise that using household cleaners on the skin is not the best idea on the planet... BUT, when you have been awake for some 36 hours and NOTHING else is helping the itch (other than paying your doctor to experiment with drugs that have many known, not so fun, side effects), I have said oh well, a little burn on the skin is more than worth the ability to sleep!!!
I do suggest you make sure to dilute household bleach somewhat, and try to apply to only to the effected areas. Using a cotton ball dab the solution on to the blisters only, this tends to work better if the blisters have opened, therefore allowing the solution to penetrate and dry the histamines out.
I would not try this if you have sensitive skin. Will also say that this may be not the best idea, do it at your own risk. (disclaimer for those who enjoy the legal side of things)
I write all this while dabbing my own newly aquire sores with Windex... don't have any bleach at the moment. :)