Gene, who is a pretty smart boy ENT by training and experience as I recall, made a good comment to the business of treating fevers.
His insights are worth reading. I have been practicing for 40 years and never saw such a cogent discussion of the subject although I surely have stood and listened to pediatricians talk to parents about fevers and febrile seizures and I have reassured parents and patients about fevers thousands of times.
From Gene on fever and treating fevers:
Depends on the tissue. For pretty much everything except brain and spinal cord, the limits are in the high forties (Centigrade)and are not attainable by fever (unless you do hard work while heavily dressed). Your testicles are on the outside, so no worries there — unless you’re heavily insulated in that area. Sustained fever helps immunity — the higher, the better.
The most limiting factor is intracranial temperature. Your #1 problem is that you start getting irreversible brain damage from prolonged hyperthermia at 39C and above (36 C is normal). What’s good for immunity is not good for sanity. The correct solution is to cool the brain while in fever: wear an ice pack on the face and the front side of the neck; check that contact is good around eye sockets, forehead and temples. In the absence of ice, a wet cloth exposed to wind will do the job (use a fan if at home). This method actually has dual benefits: if applied properly, it raises core temperature while cooling the brain (a direct consequence of cooling — if you see this effect, it means your cooling effort has reached the hypothalamus).
The chills and aches you get all over the body are the signs that your spinal cord is not happy. There is no good solution for that; however, it seems like the spinal cord more resilient to hyperthermia than the intracranial parts.
I never treated my children’s fever. I simply wrapped them in blankets and took them outside for anywhere between half-hour and two hours at a time with their heads uncovered (they always happened to be sick in the dead of winter, so ambient air was as good as ice). We never had seizures or anything as dramatic; the earliest signs of brain damage I detected were reduced activity and the loss off vergence control (like when falling asleep, just more sustained and not quite reaching the sleep phase). They regained vergence and felt better within minutes of cooling, sometimes properly falling asleep. We glided through all the horrible childhood infections without any damage, and now they are pretty robust adults, compared to most of their peers.