Yes it is safe as long as you don't put it in for really long lengths of time. I find they hold the heat better than plain cotton. Flannel is good and what I usually use with an outside case to be removed for washing. I have never used any scents in them and was wondering how you use the oils or cinnamon? Do you use just a stick and crush it or put it in whole?? or use the powder. could someone talk about these!!! :?: Jan