Hi. I was having a problem with a red, stinging rash after every class. I ruled out towel friction, detergent, and soap as the problem. Then another yogini with background in nutrition suggested that I stop eating refined sugar–said that sometimes the heat/sweating are a problem with people who eat a lot of sugar. I have nearly eliminated sugar from my diet, and I no longer have any rash problem at all. (I use honey, maple syrup, etc. in small amounts.)