FIR saunas don't necessarily promote sweating, do they? If they don't then I don't recommend them all that often. The body works very hard to maintain a certain temperature, and unless a temp change is accompanied by sweating, you're not detoxing, you're just heating/baking.

The detox baths promote release of toxins through our largest organ, skin. Skin is basically our third kidney. My understanding is that FIR (Far-Infrared-Sauna) saunas go right to the interior, working inside-out. I'm suspicious of such things until there's a good body of anecdotal evidence.

A detox bath gives one instant results, you can immediately feel it. If a FIR (Far-Infrared-Sauna) sauna does not, then I wouldn't bother with it more than once a week, and only then if you suffer from disorders of cold. A better way to warm the organs in order to tonify them is moxibustion acupuncture. Lots of anecdotal evidence supporting that. :) It's a kind of warmth that doesn't strain the heart or force it to increase blood pressure and heart rate to cool the blood down.