Half the time when I feel like Ive got a fever and take it.. I actually do. Actually a hospital was the first ones who made me aware that I get fevers without even knowing I have one (as they pointed it out to me that I was running fevers when I was in hospital one time, nurses kept becoming concerned when taking my temp .. I ended up having to tell them not to worry about the fevers as I felt fine and they were normal for me due to the ME. Ive got a lot of fevers since the start of the ME (originally I used to always run extremely high fevers whenever I was sick with the ME). I have also been thinking of late about if autonomic issues could be involved in some of my fevers as I know they can affect temp regulation. I think thou it is likely that my fevers may be reacting viruses??? as I often also get a sore throat (recently too noticed I was having outbreaks of herpes with ME crashes) or maybe sign of inflammation as I also was almost in the abnormal range (on the border at times) with inflammation markers. But thanks for your post.. it is another issue to watch out for.. autonomic dysfunction causing fevers.