I have used a FIR (Far-Infrared-Sauna) sauna for over 2 years and though it has helped to detox to some degree and I don't have colds, I've had to rethink the use of the sauna as I have developed congestive heart failure and my skin has become cooked looking, especially on my arms. (I drank water before and after). I know about cooking and you can dry a piece of meat at the temp. 130 plus temp. which is what I had to use in order to sweat. I used the sauna 3-4 times a week and enjoyed it but I may have overdone a good thing since the FIR (Far-Infrared-Sauna) penetrates the skin so deep (even to the heart area).
I called the company where I bought my sauna and put the idea to him about slow cooking our bodies with FIR (Far-Infrared-Sauna) and he said that doesn't happen. (Heat is heat and dries flesh) But I would like to know if other FIR users have found their skin looking baked and having heart problems.