I have been using the Karin Herzog products for years and have had no problems at all but only great results. In my case there was the sweating you describe but that has to do with the oxygen which cleanses the skin from the inside out. This was only apparent in the beginning for a couple of months until the oxygen levels under my skin was regulated and the pores were cleansed.Good question! Because it's cheap, I guess!
Some European companies formulate their cosmetics with PHARMACEUTICAL grade mineral oil and claim it is actually good for the skin. Karin Herzog and Gerda Spillman are 2.
Here is a link that says mineral oil may block the pores and cause blackheads and prevent perspiration from escaping. That doesn't sound good!
I know that the Karin Herzog products are some of the very few products that do not contain preservatives and are a non-aggressive therapy method. What makes them quite special is that their products that contain oxygen do not require preservatives. I am a bit of a freak when it comes to what products I put on my face and what I feed my children etc.