Unfortunately, we don't have a very good selection of DMSO here in the USA and the USP grade stuff is way over-priced and needs a prescription. Lastly, most of the cheap DMSO over here is China based which probably is not good, but I am still of the mind that any DMSO is better than none. It is that non-toxic and good!
DMSO will not burn skin, it will draw water out of it and dry it out. It can also cause some itching in some people
I just obtained a copy of Dr. David Williams' book, "DMSO, The Complete Up-to-Date Guidebook' (1993). In it I found interesting that he said the only difference between industrial grade DMSO and pharma grade was this:
"Basically, prescription DMSO goes through two procedures that "over-the-counter" DMSO doesn't.
1) it is sterilized by filtration.
2) it is pyrogen tested.
To sterilize DMSO, the product is passed through a very fine filter that removes any particles the size of bacteria and larger. Most researchers, clinicians and medical professionals consulted, questioned the need for sterilization. If you remember DMSO is bacteriostatic at concentrations of 35% or above; at these concentrations, it stops bacteria growth.
Pyrogen testing is a costly and time consuming procedure. A pyrogen is any substance that causes a fever. To test a batch of DMSO for pyrogens, laboratory animals treated with the drug and then their temperatures are monitored on a regular basis. This procedure is felt by many to be another instance of FDA "overkill". Most informed authorities agree that pyrogen testing is definitely not necessary for DMSO intended for topical use. Many even question its necessity for DMSO used to treat interstitial cystitis by catheter."
I say to this, if this is true, one can easily filter over-the-counter DMSO with .22 micron filter set-ups and save hundreds of dollars. When choosing a filter material to filtrate DMSO, it is good to know this:
DMSO is incompatible with polysulfone, flexible and rigid PVC tubing and polycarbonate.
It is moderately compatible with polystyrene and ECTFE/ETFE.
It is compatible with LDPE, HDPE, polypropylene, PPCO polypropylene copolymer polymethylpentene,
nylon and teflon FEP type filters.