eli5: If fever is our body’s response to kill an infection, then why do we take medicines like paracetamol that control the fever?

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Also, I get that the fever can get really high at some point, which causes other effects, but why is our body not able to control its response to the infection so as to not do more harm with the fever?

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33 Answers

Anonymous 0 Comments

Fever is a catch all that doesn’t work on everything, so sometimes it just makes you feel worse without doing much, and in that case, taking fever reducers makes a lot of sense. For illnesses that fever does help with, sometimes the thought process is that dragging it out but feeling alright is preferable to recovering quicker but being debilitated while sick

Anonymous 0 Comments

For why fevers can cause more harm than good in some cases, fevers are built for communities, not individuals. If you die from your fever, the disease does too, and the herd (which shares the fever gene) survives.

A fever that turns off when you get too hot would be much more complex to develop, potentially could more easily fail to stop the disease before it spreads, and likely wouldn’t do much for a community at large than just turning the fever on and playing chicken with the disease does, so the simple [fever on when sick] approach is where evolution landed.

We suppress it because modern medicine can target the right thing more often than a fever can. Sometimes a fever won’t help, other times we can fight the sickness better a different way, and either way preventing spread so aggressively is less important with modern hygiene.

Anonymous 0 Comments

For why fevers can cause more harm than good in some cases, fevers are built for communities, not individuals. If you die from your fever, the disease does too, and the herd (which shares the fever gene) survives.

A fever that turns off when you get too hot would be much more complex to develop, potentially could more easily fail to stop the disease before it spreads, and likely wouldn’t do much for a community at large than just turning the fever on and playing chicken with the disease does, so the simple [fever on when sick] approach is where evolution landed.

We suppress it because modern medicine can target the right thing more often than a fever can. Sometimes a fever won’t help, other times we can fight the sickness better a different way, and either way preventing spread so aggressively is less important with modern hygiene.

Anonymous 0 Comments

Fever is a catch all that doesn’t work on everything, so sometimes it just makes you feel worse without doing much, and in that case, taking fever reducers makes a lot of sense. For illnesses that fever does help with, sometimes the thought process is that dragging it out but feeling alright is preferable to recovering quicker but being debilitated while sick

Anonymous 0 Comments

There’s some thought to try controlling fevers less now than in the past, so even doctors are still asking this question.

Anonymous 0 Comments

There’s some thought to try controlling fevers less now than in the past, so even doctors are still asking this question.

Anonymous 0 Comments

The body’s fever response isn’t exactly a precision tool. Sometimes a fever gets higher than necessary. Also, research suggests that suppressing a fever using over-the-counter drugs does not substantially prolong diseases like the flu or common cold. So there is very little harm, if any, and on the flipside suppressing your fever can make you feel much better.

The immune system is simultaneously very complex, powerful and adaptive in some respects, while also being primitive and dumb in others. It’s also not just one system – it has multiple components with various degrees of finesse. When you first get infected with a pathogen for which you do not have an immune memory, the first responders of your immune system are of the dumb, primitive type whose motto can be summed up as “set fire to everything that looks bad”. If your immune system is an air force, these are its carpet bombers. They kill the enemy, but they also do a lot of collateral damage. This is your *innate* immune system.

Your *adaptive* immune system is much more of a precision-bombing, navy seals type of operation. But it needs time to gather intel on the enemy. Once it has that, it can mount a massive precision operation throughout the body that rounds up all the enemies while being much less dangerous to civilians. Once this part of your immune system kicks in, you usually start feeling better pretty quickly, and your fever will also subside.

Why is your body not able to control the fever itself? Because evolution is not a purposeful, intelligent process. It just keeps the stuff that works most of the time. The human body (like every other species) is a whole bag of ad-hoc solutions that have been duct-taped together. It’s not engineered to work well in all edge cases. It’s built to work most of the time, and evolution doesn’t care about the minority of cases when it doesn’t. That even means your own body can kill you in rare cases, and when it does the immune system is often the culprit, because it’s just so damn complex that it’s easy for things to go wrong. Complex systems have more edge cases than simple ones, like, say, your heart, which is just a big ol’ pump.

Anonymous 0 Comments

The body’s fever response isn’t exactly a precision tool. Sometimes a fever gets higher than necessary. Also, research suggests that suppressing a fever using over-the-counter drugs does not substantially prolong diseases like the flu or common cold. So there is very little harm, if any, and on the flipside suppressing your fever can make you feel much better.

The immune system is simultaneously very complex, powerful and adaptive in some respects, while also being primitive and dumb in others. It’s also not just one system – it has multiple components with various degrees of finesse. When you first get infected with a pathogen for which you do not have an immune memory, the first responders of your immune system are of the dumb, primitive type whose motto can be summed up as “set fire to everything that looks bad”. If your immune system is an air force, these are its carpet bombers. They kill the enemy, but they also do a lot of collateral damage. This is your *innate* immune system.

Your *adaptive* immune system is much more of a precision-bombing, navy seals type of operation. But it needs time to gather intel on the enemy. Once it has that, it can mount a massive precision operation throughout the body that rounds up all the enemies while being much less dangerous to civilians. Once this part of your immune system kicks in, you usually start feeling better pretty quickly, and your fever will also subside.

Why is your body not able to control the fever itself? Because evolution is not a purposeful, intelligent process. It just keeps the stuff that works most of the time. The human body (like every other species) is a whole bag of ad-hoc solutions that have been duct-taped together. It’s not engineered to work well in all edge cases. It’s built to work most of the time, and evolution doesn’t care about the minority of cases when it doesn’t. That even means your own body can kill you in rare cases, and when it does the immune system is often the culprit, because it’s just so damn complex that it’s easy for things to go wrong. Complex systems have more edge cases than simple ones, like, say, your heart, which is just a big ol’ pump.

Anonymous 0 Comments

Because we can. A high fever tends to make you feel shitty, so if you have the chance to feel better, (or make your kid feel better) most people will take it.

I do believe that a lot of people do it too quickly, though.

I go by the rule of thumb our pediatrician gave me: Ease pain, not fever. So if my kid or me has a high fever and is suffering, I will give a dose of tylenol. But especially for my kid, I tend to underdose so the fever doesn’t go away completely but is just lowered a bit to make him feel a bit better.

Because one good thing a fever does is to make you want to stay rest in bed. Experience shows that once my kid has had a full dose of tylenol, he’ll be bouncing off the walls because he feels just fine but I know it’s just a superficial thing and his body is still fighting the infection and could really use some rest.

So what I aim for is some relief instead of the feeling of being completely fine right away. I do the same for myself. I tend to wait quite long before taking a dose of ibuprofen and when I do, I only take a small one.

Anonymous 0 Comments

Because we can. A high fever tends to make you feel shitty, so if you have the chance to feel better, (or make your kid feel better) most people will take it.

I do believe that a lot of people do it too quickly, though.

I go by the rule of thumb our pediatrician gave me: Ease pain, not fever. So if my kid or me has a high fever and is suffering, I will give a dose of tylenol. But especially for my kid, I tend to underdose so the fever doesn’t go away completely but is just lowered a bit to make him feel a bit better.

Because one good thing a fever does is to make you want to stay rest in bed. Experience shows that once my kid has had a full dose of tylenol, he’ll be bouncing off the walls because he feels just fine but I know it’s just a superficial thing and his body is still fighting the infection and could really use some rest.

So what I aim for is some relief instead of the feeling of being completely fine right away. I do the same for myself. I tend to wait quite long before taking a dose of ibuprofen and when I do, I only take a small one.