Before the days of antibiotics did they not use sunlight to help heal wounds????
I got the idea of UV light from the way sunlight has cured fungal infections for me. On the rare times I've had either crotch rot or athlete's foot, sunlight has been the best and quickest cure. I read that doctors on Corregidor put gangrene wounds in direct sunlight when they ran out of medicine, and it worked.
I bought mine from Amazon or Ebay, called a portable disinfection light, battery operated. Think I paid $19 for it. It claims "up to" 99.99% sterilization, but the fine print mentions time exposure and very close to item being disinfected. I've used it on two infections and it killed/cured both within hours.
Re hydrogen peroxide on skin: a Dr. told me the same, that it kills a lot of good cells along with the bad. I have used it anyway because IME it usually helps overall healing.
