ELi5 Why are fevers so dangerous? If they’re an immune system mechanism, shouldn’t there also be a biological “emergency stop/ brain overheating” button?
In: Biology
There are a lot of incorrect answers in this thread.
Fevers are not well understood. The pathways and cell signals that activate it are still a source of contention in science, along with why fevers evolved and if they are still beneficial. In fact, there’s not even an agreed upon limit of [what temperature constitutes a fever](https://en.wikipedia.org/wiki/Fever#:~:text=There%20is%20no%20single%20agreed%2Dupon%20upper%20limit%20for%20normal%20temperature%3A%20sources%20use%20values%20ranging%20between%2037.2%20and%2038.3%C2%A0%C2%B0C%20(99.0%20and%20100.9%C2%A0%C2%B0F)%20in%20humans.) or whether [reducing a fever actually does anything](https://en.wikipedia.org/wiki/Fever#:~:text=While%20fever%20evolved%20as%20a%20defense%20mechanism%2C%20treating%20a%20fever%20does%20not%20appear%20to%20improve%20or%20worsen%20outcomes.).
So, it’s complicated. But generally speaking, when a fever becomes too high it’s a sign that something is seriously wrong with the body; that is to say, whatever caused the fever is going haywire and the body’s ability to fight back properly is impaired. It’s like asking “why can’t a broken machine fix itself?”. At this point medical intervention is required like strong antibiotics and antiviral medication.
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