Are there any possible negative side effects to using eucalyptus oil in an infrared sauna long term?k

Possibly : Can develop a sensitivity to the eucalyptus oil (irritant dermatitis). I have to work within a conventional medical framework and in the conventional world the studies on infrared saunas have so far been disappointing re its effects.

None known: Eucalyptus oil has many proven healing benefits. Inhaling the vapors in a sauna is beneficial for lungs and sinuses. You can have too much of anything so excess amounts might cause irritation of your eyes, lungs or sinuses or dizziness, but this would be an acute reaction and there is no known problem using small amounts long-term. See http://tinyurl.com/qa6zpkr for info on eucalyptus oil.