Yes, as Traveler stated, my husband used it full potency on several trouble areas.
One was his back - but it was more in the right thoracic area of his back. (injury from a car accident - pain was persistent - and I think it was a year after the accident (or longer) when he used the DMSO.
Make sure whatever you use to apply it is clean...it will carry dirt..etc. through the skin into the blood stream.
and also the area you are applying it to must be clean.
My husband used it full strength....and he applied it several days in a row. The skin was red...felt like a burn..and then itchy.
He got very quick relief - either by the next day or a couple days.
He swears by it.
I tried it on my left hand pre-diagnosis...just once...and I didn't notice anything...but my pain could be referred nerve pain...then I never applied it a second time.
I'm a chicken though. I came close to doing the LDI and never followed through with it.