Right Jay, The dmso is a solvent....it does increase penetration significantly......it is usually added at a 10% ratio or 24ml in 240ml solution. It will give a slight odor and sometimes you can taste it 'on your breath'.....this is a sure sign that your transdermal is penetrating the skin. Some peoples skin is more delicate than others and will develop rash. I applied to the same areas for 4wks and saw no rash. Mix it, shake it, apply and grow. Good luck.