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
>ELi5 Why are fevers so dangerous?
They are not.
Fevers are not dangerous. They cannot harm you.
>shouldn’t there also be a biological “emergency stop/ brain overheating” button?
There is. Part of your brain (the hypothalamus) regulates your body temperature. Under ordinary circumstances, it is very effective.
A very high body temperature can be harmful, but this is not from a fever (which is your body’s response to an infection), but from factors that overwhelm your body’s ability to control its own temperature, such as very high ambient temperature and humidity, medications that prevent sweating or increase the body’s production of heat beyond its ability to shed heat.
But a fever itself does not cause harm.
Source: I am an emergency physician.
i hate it when my computer overheats and just shuts off, the human on-button harder to find.
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.
I think OP might be confused by older generations with myth that fever causes brain damage when it’s actually the other way around: bacterial meningitis leads to both high fever and brain damage untreated.
Evolution is generation after generation of “good enough”. Good enough for what? Good enough that enough of the current generation will survive to reach adulthood and reproduce to produce the next generation. As long as you can check that box whatever else is going on is “good enough”.
For most of human history half of children would die before the age of five. And you just had myrtle squirt out a replacement and it was “good enough”. It’s terrifying to realize just how much dysfunction and bad design can fit into “good enough”.
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