Eli5: How does a fever work?



If you have a fever how is the best way to break it? I was told as a child to add layers to “break” the fever. But now I’m told that’s wrong. What is a fever and how does it work/stop?

In: Biology

Imagine you and 5 friends are hanging out on your patio. It’s a beautiful day and your are all watching football on your outdoor TV. Then, out of nowhere, your neighbor Karen comes walking down the street, walks onto your property, and uninvitedly joins the party. She then flips over your bowl of tostitos and throws your salsa all over the patio. Karen is clearly messing up your party and making it less enjoyable. You need her to leave but telling karen to leave is not an option as she has made her place on your patio. So, you come up with a new idea, instead of asking karen to leave, you are gonna create a social environment so poor for Karen that she is going to have a hard time continuing to destroy your party. So, you change the channel and put on an old western w/ the volume cranked. Then, since you and your friends have just finished off a plate of hot dogs, you begin farting. You all keep farting, louder and louder, and you keep increasing the volume of the western. Karen, now in an environment that is not pleasing to her, leaves your patio, and you and your friends return to watching the game happily. In this example, Karen is a virus/bacteria and the farting and watching a loud western is a “fever”.

A fever is a defense mechanism of your body. When a bad thing enters your body (virus, bacteria), your body, wanting to get rid of this invader, responds by heating up as it cannot simply ask the invader to leave. This creates an environment that makes it more difficult for that virus/bacteria to survive/reproduce. One method your body uses to heat up that everyones familiar with is “the chills”. Your body tricks your brain into thinking it’s cold and your brain instructs your body/muscles to shiver to create more heat to drive your body temperature up. Your fever permanently breaks when your body has fought off a significant amount of the foreign invader, as your body no longer needs to create an environment unfavorable for the invader and can return to its normal, optimal temperature for your essential body processes. Unfortunately, your normal bodily processes also suffer a bit when you have a fever b/c the body is no longer at an optimal temperature for those processes to run (you and your friends missed some of the football game and also didnt have much fun during the farting/western watching session).

Adding layers will help insulate your body to drive your fever up (bringing karen and your friends inside and farting/watching a loud western in your secret room under the stairs), this might temporarily help you feel better as it can stop your chills but it does not break a fever.